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IME^Ik 5 

Gift of 
Dr. Grant Self ridge 



Gift of 

Dr. Grant Self ridge 




5 £ S 



•.AVk^ \}.i). 

\ ■ 

*" 1 ■ ** 



Its Physics, Physiological Action 
and Therapeutic Applications 


Fellow of the New York Academy of Medicine ; Fellow of the 
American Electro-Therapeutic Association ; Member of the New 
York County Medical Society ; Fellow of the Societe Franchise 
d'filectrotherapie ; Fellow of the American Electro- 
Chemical Society ; Member of the Society of American 
Authors ; Member of the New York Electrical 
Society; Professor of Light Energy in the New 
York School of Physical Therapeutics; 
Late Instructor in Electro-Thera- 
peutics in the New York Post- 
Graduate Medical School 


" But if darkness, light and sight be separate and independent 
one of the other, then if you remove light and darkness, there is 
nothing left but void space."— Buddhistic Sutra, 



10 West 230 Street, Cor. 5TH Ave. 129 Shaffesbury Avenue, W. C. 


Coi'YRir.HT, I</>4 

By Reiiman Company, New York 

Copyright, 1904 
By Roman Linutki*, Lonpon, Knci.and 




8201 7 



The subject matter of this volume on Light Energy, as 
applied to medicine, has been the outgrowth of eleven years' 
clinical experience with that part of the subject covered by 

Its formal presentation to the profession is due to the 
constant demand on the part of physicians seeking post- 
graduate instruction at the author's hands that she should 
embody her experience in the form of a book. 

Its pages are devoted to a practical consideration of the 
physics, physiological action and therapeutic effect of light 
energy from both natural and artificial sources, and also 
aim to give a compendium of the literature of this new sub- 
ject up to date of going to press. 

Vacuum tube discharges and radio-active substances are 
also considered from the physical, physiological and thera- 
peutic points of view. 

The Roentgen ray has not been considered, although 
properly belonging to a consideration of light energy, for 
the reason that the subject has been most exhaustively 
covered by others, and books on Radiotherapy exist in 
sufficient numbers. The Roentgen ray is, therefore, re- 
ferred to only incidentally in its relation to light and radio- 
active substances, in order to establish as clearly as possible 
the indication for the one or the other. In the therapeutic 
uses of etheric vibrations, differing only in degree not kind, 
it is difficult to draw a line of demarcation, to say when 
the irregular discontinuous impulses of the Roentgen ray, 
itself of the nature of a single ultra-violet ray, should be 
used, ?nd when the rhythmic orderly procession of the short 


high-frequency vibrations of intense chemically active 
is indicated. The author will feel that her labor is ft 
vain if the indication! at hast f-»r the use of light energy 
are clearly set forth. 

No apology is offered t lering .it length the fun- 

damental physics of light ener • - 1 , * 1 1 >- in so far as the 

physical laws governing light heir upon its thcrap- 
application* To those more Of - ts< lamiliar with 1 1 1* - <ttl> 
ject, it mav open np a line of itndj fascinating in the 

treme. The electric arc has been treated of iti com 

detail, as Upon it the physician's main dependence must be 

placed for a source of artificial light rich in chemieally 

active energy. The effort baa been to elucidate those points 

only in its physics which her own pe rs o na l experier 
its use had indicated as essential. 

The author*! own method! of utilizing light « 
with results have heen given, and also the experience 
others as well. I pinion formulated bj Othefl has 

heen carefully analyzed, and the conclusions drawn there- 
from submitted to vigorous criticism, especially from the 
physical side, before givhtg them place in these pages, 
Especially has care heen taken to exclude am * not 

based upon EOtmd fundamental physical laws. It matters 
not what form of energy is expended within the ttSSIti 
the fundamental physical laws of that energy are known, 
and its physiological action, the therapeutic application In- 
comes a very simple matter, involving no other principles 
save those fundamental to the physician. 

Upon physical laws and p roperties, physiological action 
and pathological conditions, the exhibition of light energy 
is at once rational and comprehensive. 

Light as a therapeutic measure, as well as a factor in 
hygiene and sanitation, ts not only of importance to-da\. 
but always will be. 

In view of the fact that the continued existence of the 
human Species OH earth depends entirely on radiant en 
no apology is necessary for presenting a volume devoted 


entirely to a discussion of light in its physical, physiological 
and therapeutical aspects to the consideration of a profes- 
sion whose duty it is to minister to human life from its first 
inception to its final dissolution. 

While light energy is as old as the sun, and so almost 
are its therapeutic uses, never in the history of medicine was 
it as fully appreciated as now. The author hopes that a 
study of these pages will teach the student that it is not only 
ultra-violet energy, but all the radiant energies of the sun 
or artificial sources of light which are necessary to the main- 
tenance of health, and to the curing of disease. She also 
trusts that a perusal of these pages will stimulate a careful 
and systematic investigation of the subject, to the end of 
placing the general use of light energy upon a foundation 
equally scientific and sure, as that upon which Finsen has 
builded his therapy of skin diseases. 

The author's acknowledgments are due to the courtesy 
of Dr. Gunni Busck, of the Finsen Lysinstitut, for the page 
proof of his work on Light Biology, which arrived in time 
for the incorporation of the most recent work upon sensitiza- 
tion of living tissues, and also for his hypothesis as to the 
sensitization of the organism by quinin in malaria. 

The author's kindest and most cordial acknowledgments 
are due her friend, Dr. Elizabeth Stow Brown, not only for 
assistance in French translations, arrangement of accumu- 
lated data and reading of manuscript, but for her intelligent 
interest in the subject. 

The author's acknowledgments are due to the courtesy of 
the British Medical Journal for the use of the cuts (Figs. 
4 and 5) illustrating the experiments of Bernard and 

The author's acknowledgments are also due her friend, 
Dr. Leslie J. Mcacham, for his untiring and intelligent 
assistance in revision of manuscript and proof. 

Margaret A. Cleaves. 
616 Madison Ave., New York City. 
Sept. 15, 1904. 



Introduction: Light Energy, the Theory of. Its Manifesta- 
tions, Radiant Heat, Brush Discharges in Vacuum, Visi- 
ble Light, Ultra- Violet Rays, N Rays. X Rays, Cathode 
Rays, Alpha, Beta and Gamma Rays 1-22 


The Physics of Light Energy and Radiant Heat. Sunlight, 
Electric Arc Light, Incandescent Light, Mercury Vapor 
Light. Spark and Vacuum Tube Discharges 23-129 


The Action of Light Energy upon Elementary Forms of ' 

Life 130-140 

The Action of Light Energy upon Vegetable Organisms 141-162 

The Action of Light Energy upon Bacteria 163-203 

The Action of Light Energy upon the Higher Organisms 204-223 


The Physical Effects and Biological Action of Light Energy. 

Skin, Circulation, Nervous System. Metabolism 224-307 


Sun Baths. Arrangements of Solaria. Methods of Use and 
Therapeutic Indications. Tuberculosis of Joints, Pul- 
monary Tuberculosis. Anaemia and Neurasthenia 308-329 




Electric Arc Baths. Arrangements of Light Mechanisms. 
Methods of Use and Therapeutic Indications. Pul- 
monary Tuberculosis, Bronchitis. Bronchial Asthma, 
Ana?mia. Neurasthenia, Locomotor Ataxia and other 
Nerve Disorders 330-396 


Incandescent Light Baths. Arrangement of Light Mechan- 
isms, Methods of Use. Therapeutic Indications. Obesity. 
Gout and Rheumatism. Diabetes. Anremia and Chloro>is, 
Toxaemias, Nephritis 397-435 


The Concentrated Visible Chemical Frequencies of the Solar 
Spectrum. Mechanisms, Methods of I'se and Therapeutic 
Indications. Malignant Pustule, Diphtheritic Croup, 
Pneumonia. Pulmonary Tuberculosis and Lupus Vul- 
garis 43 n -45 ( > 


The Concentrated Energy of the Electric Arc Spectra. Car- 
bon. Carbon and Iron. Iron. Mediani-nis. Methods of 
Use and Therapeutic Indications. Lupus Vulgaris. Lupus 
Erythematosus. Sycosis. Eczema. Tubercular I'lccrs. 
Tubercular Glands. Neuriti-. Neuralgia^ Finsen 4'x>-539 


The Concentrated Energy of Incandescent Light Spectra. 
Mechanisms. Methods of I'se and Therai)eutic Indica- 
tions. Local Incandescent Baths. Rheumatic Joint*. 
Chronic Synovitis, etc. Incandescent Light in Gyne- 
cology 54° 55 <s 


The Exclusion of All but the Frequencies of the Blue 
Region of the Spectrum, or the Visible Chemical Fre- 
quencies. Blue Light as by the Method of Kai-e'- and 
Minim; Its Therapeutic Indications. Contusions. Sprains, 
Open Wounds and Tuberculosis of Joints 55V-5$i 



The Non-Concentrated Frequencies of the Red Region of 
the Spectrum or Red Light. Exclusion of all Above the 
Red in Smallpox and the Exanthemata. Finsen 582-601 


The Concentrated Invisible Chemical Frequencies of the 
Spectrum or Ultra-Violet Rays. Mechanisms. Spark 
Condenser Lamps Excited by Alternating Currents, High 
Frequency Coils or Static Machines, Methods of Use and 
Therapeutic Indications 602-648 


Vacuum Tube Discharges, Phenomena and Theory of. 
Mechanisms, Methods of Use and Therapeutic Indi- 
cations 649674 


N Rays. Their Place in the Spectrum and Relation to the 

Living Organism. Blondlot and Charpentier 675-692 


Alpha, Beta and Gamma Rays of Radio-Active Substances. 
Uranium, Thorium, Polonium, Actinium and Radium. 
Radium : . Its Physics, Physiological Action and Thera- 
peutic Value. Prof, and Mme. Curie 693-750 


Fluorescence, Fluorescent Stimulation. Sensitization. Thera- 
peutic Uses in Cancer, Lupus Vulgaris, Condylomata, In- 
durated Chancre and Malaria 751-788 


The Pernicious Effect of Sunlight; Insolation. Pathological 

Effects of Electric Lighting. 789-81 1 



i. Arc Light Carbons Showing Positive Crater and Nega- 
tive Nipple, etc facing 89 

2. Langley's Plate, Showing Energy Curve of Different 

Sources of Light facing 128 

3. Langley's Plate, Showing Energy Curve, Sun and Firefly 

Spectra facing 128 

4. Experiment with Dead Frog's Foot . . . facing 182 

5. Action of Ultra- Violet Light on Bacteria . . facing 182 

m ' ) Sections Showing Action of Light upon the Skin. 

'' 1 Moller facing 252 

9. Fraunhofer's Lines facing 252 

10. Arc Light Cabinet facing 334 

11. Diagram Indicating Luminous Intensity Alternating-Cur- 

rent Arc 394 

12. Diagram Indicating Luminous Intensity Continuous-Cur- 

rent Arc 394 

13. Incandescent Cabinet, open .... facing 402 

14. Incandescent Cabinet, closed .... facing 402 

15. Sun Lens, facing 438 

16. Diagrammatic Cut of Finsen's Concentrator . . . 466 

17. Finsen's Apparatus 467 

18. Compressor 470 

19. Victor Lamp 473 

20. Lortet-Genoud Lamp ........ 473 

21. Marine Searchlight, with Blue Glass Screen . facing 478 

22. Marine Searchlight, on High Stand . . facing 478 

23. Marine Searchlight, with Funnel - shaped Attach- 

ment facing 480 

24. Iron Electrode Lamp 485 

25. Piffard Iron Electrode Lamp 487 

26. Compressor 497 

27. Compressor . . ' 497 



28. Giant Cell from a Case of Lupus after Two Light Treat- 

ments ........ facing 536 

29. Section of Lupus Nodule after Four Light Treat- 

ments facing 536 

30. Local Light Baths facing 542 

31. Water-cooled Vaginal Lamp .... facing 542 

32. Minim Lamp ......... 579 

33. Electroscope 614 

34. Ultra- Violet Rays Discharging a Piece of Zinc . . . 618 

35. The Gorl Lamp ........ 624 

36. Showing Connections for Ultra- Violet Lamp with Leyden 

Jars in circuit 625 

37. Line Cut Showing Method of Securing Ultra-Violet Rays 

from Alternating-Current Mains 628 

38. The "Ultra-Violet" Lamp facing 630 

39. Cut Showing Upward Movement of Spark through Ionized 

and Heated Air 662 

40. Interrupters 668 

41. Vacuum Tubes with Leading-in Wires .... 669 

42. Vacuum Tubes without Leading-in Wires .... 670 

43. Strutt's Apparatus for Demonstrating the Absorption of 

Radium Radiations 704 

44. Paschen's Modification of Above ..... 705 

45. Line Cut Showing Magnetic Field of Radium . . . 708 

46. Radium-graph of Mouse facing 718 

47. Radium-graph of Dead Human Hand . . facing 718 

48. Radium-graph of Mouse in Trap . . . facing 719 

49. Diagrammatic Representation of Seed-growth under 

Radium 743 

50. Radium Receptacle for the Stomach ...... 749 

51. Radium Receptacle for the (Esophagus and Rectum . 749 

52. Radium Applicator Set, No. 1 ... facing 750 

53. Radium Applicator Set, No. 2 ... facing 750 

54. Therapeutic Arc Lamp facing 462 

55. The Cleaves Arc Lamp facing 4»4 


Introduction: Light Energy, the Theory of. Its Manifestations, 
Radiant Heat, Brush Discharges in Vacuum, Visible Light, 
Ultra- Violet Rays, N Rays, X Rays, Cathode Rays, Alpha, Beta 
and Gamma Rays. 

Light Energy. 

Energy is defined by Professor Barker "as a condition of 
matter in virtue. of which any definite portion may effect 
changes in any other definite portion." It is regarded as 
the potential of the universe, and when matter is in a phase 
permitting activity, all other quantities of a matter at a 
distance are affected. The method of transfer of energy 
through space is universally conceded to be by means of 
wave motion through the ether, the eternal recipient and 
universal transmitter of Nature's infinite energy. Through- 
out space all matter is vibrating from the lowest musical 
note to the highest pitch of the chemical rays. The various 
manifestations of energy known as sound, heat, light, elec- 
tricity and chemical action, are all vibrations of this uni- 
versal, homogeneous, incompressible continuous body, which 
is incapable of being resolved into simpler elements or 

These various manifestations of energy are recognized 

as such according as they are perceived by different nerves, 

for the mind of man translates the impressions of the world 

^i into facts of consciousness and thought by means of the 


nerves of the human body. All these varying rates of vibra- 
tion, differing as they do only in direction, rate and fre- 
quency, are interpreted according to the different nerves or 
groups of nerves physically attuned to them, or organized to 
select and respond to especial manifestation of vibratory 
activity. The optic nerve transmits to the retina and the 
brain the sensation of light, and its function is limited to the 
phenomena of radiation. It is wonderfully sensible to cer- 
tain impressions of this class, but on the other hand is very 
little affected by, even obtuse to other impressions. Vibra- 
tions which affect the sense of touch, taste, smell or the 
senses can be educated to take the place of the optic nerve 
to a very great extent, functioning in such a way as to carry 
correct impressions, ordinarily received by way of the optic 
nerve, to the brain. Nor does the optic nerve perceive the 
entire range of radiation. Its function is not excited by all 
the rays which reach it, while there are others which never 
reach it at all, being absorbed by the humors of the eye, and 
producing thereby the brilliancy characteristic of it. Invisi- 
ble rays are emitted by non-luminous bodies, as there is no 
body in nature absolutely cold, and every body not abso- 
lutely cold emits rays of heat. But in order that radiant 
heat may affect the optic nerve a certain temperature must 
be reached. As the temperature is increased, in a platinum 
wire, for example, through which a gradually increasing 
current is sent, the wire, by reason of its great resistance, 
first becomes warmer to the touch, then increasingly warm, 
next glowing with a red light, and as the current is increased 
becoming brilliantly incandescent. 1 This phenomenon, which 
is comparable to the light of the sun, affects the retina and 
excites the sensation of vision. 

The author's conception of light and its action is based 
upon the now accepted undulatory theory, and is coupled 
with the belief that all space is saturated with the incon- 
ceivably minute corpuscles discovered by J. J. Thomson. 2 

'Tyndall : Fragments of Science "Radiation." 

2 J. J. Thomson: Conductivity of Klcctricity through Gases. 


These are regarded as either electricity in its ultimate refine- 
ment, as very closely allied to it, or its immediate carriers. 
The "corpuscle" of Thomson is only the one-thousandth 
part of the mass of any known particle of matter. The 
astro-physicists, who accept the corpuscular theory, believe 
"that the earth and sun, all suns and dark bodies in space, 
all granular matter, move through the primordial cosmical 
mass of electrical corpuscles as would a wire screen through 
water.'' 1 These bodies, smaller than atoms, are able to pass 
through the wide spaces, comparatively speaking, of dia- 
monds, glass, steel, flint, etc. 

Thomson's corpuscles are positive, and negative in their 
electrical discharges, the positive carriers of electricity hav- 
ing a size comparable to ordinary atoms of gross matter, but 
the corpuscles that flow between the atoms of all types of 
matter are negative. Matter in a state of activity sends 
out continuously the same kind of corpuscles that fill all 
space. The sun in its never-ending state of activity, tur- 
bulent, tossed into fantastic shapes, is to be regarded as a 
source of negatively electrified corpuscles which stream 
through the solar system. 

The most intense radiance known is that of sunlight, and « 
when put in candle-power, the figures are so enormous as 
to convey but little idea to the mind of its intensity. 
i>,oco,oco,oco^ or fifteen hundred 

and seventy-five billions of billions enumerated according 
to the English method. 2 

Langley made a careful comparison between the solar 
radiation and that of the blinding surface of the molten 
metal in a Bessemer converter. The brilliancy of this metal 
is so great that the dazzling stream of melted iron, which is 
poured in at one stage of the proceedings to mix with the 
metal already in the crucible, "is deep brown by comparison, 
presenting a contrast like that of dark coffee poured into a 
white cup." In conducting his experiments every ad van- 

parkin : Radiant Energy. 
2 Young: The Sun. 


tage was given to the metal in order to institute a comparison 
between the brilliancy of the metal and the sunlight. No 
allowances were made for the losses encountered by the lat- 
ter during its passage through the smoky air of Pittsburgh 
to the reflector, which threw its rays into the photometric 
apparatus. Despite this disadvantage the sunlight came out 
five thousand three hundred times brighter than the dazzling 
radiance of the incandescent metal. 

The radiant energy falling ujxm the deck of an ocean 
liner is sufficient, if it could Ik* utilized, to propel the ship 
with greater speed than is now obtained from carl>on f if the 
radiation received were not cut off by the air. The air cuts 
off fully one-third. 

On an ostrich farm in South Pasadena is a great solar 
motor which has an indicated output of 11 horsepower, with 
210 pounds of steam, which can pump water at a maximum 
rate of 1,400 gallons per minute. 1 

The inconceivably rapid and minute oscillating light cor- 
puscles of the invisible region beyond the violet have a chem- 
ical energy so intense as to destroy micro-organic life, to 
wreck the molecules of nitrite of amyl, of iodine vapor, 
to produce erythema of the skin and underlying changes; 
effects dependent upon the accumulation of the periodical 
strokes of their oscillating swing until the atoms upon which 
their timed impulses impinge are jerked asunder. It is this 
energy in its various manifestations to which this volume 
is devoted. When light is conceived of in this manner, the 
reason for its power in continuing life and in curing disease 
becomes evident at once. 

Theory of Light. 

Various hypotheses have l>een formulated in order to 
explain the origin and transmission of light. 

The most important of these are the emission or cor- 
puscular theory and the undulatory theory. 

'Larkin : Radiant Energy. 


On the emission theory it is assumed that luminous 
bodies emit, in all directions, an imponderable substance 
which consists of molecules of extreme degree of tenuity; 
these are propagated in right lines with an almost infinite 

On the undulatory theory of Huygens, light consists of 
wave motions of the ether, the vibrations being transmitted 
from particle to particle with an extremely high velocity in 
straight lines ; the vibrations of the particles of the ether are 
at right angles to the path of the ray. 

An idea of this wave motion may be given by shaking a 
rope at one end, the vibrations, or to-and-fro movements of 
the particles of the rope are at right angles to the length 
of the rope, but the onward motion is in the direction of the 
rope's length. 

The luminosity of a body is clue to an infinitely rapid 
vibratory motion of its molecules which, when communi- 
cated to the ether, is propagated in all directions in the forms 
of spherical waves, and this vibratory motion, being thus 
transmitted to the retina, calls forth the sensation of 

The emission theory was supported by Newton, and is 
spoken of as Newton's corpuscular theory. Euler enun- 
ciated the undulatory theory subsequently to Huygens. 
Since the discovery of the Thomsonian corpuscle and radium 
the question has arisen as to whether there will not be a 
reversion to the emission or corpuscular theory. The un- 
dulatory theory stands, however, and upon it many optical 
phenomena, particularly those of diffraction, as shown by 
Young, can be explained. Energy is the potential of the 
universe. When matter is in a phase permitting it to be 
active other quantities of matter at a distance are affected. 
This transfer is known to be by means of wave motion. 
Each separate impulse moves from the emitting to the receiv- 
ing mass on a rigorously straight line. One individual con- 
tinuous set of oscillations in this straight line is called a ray. 
If all space is saturated with the inconceivably minute cor- 

UGH 1 

puscles of Thomson, as there is reason <<• I ich nega- 

rhomsonian corpuscle makes a double vibration to and 

fru tike a pendulum (the b lion to-aud-fro of the rope 

illustration* straight across the direction of the ray, 

at right angles to it. The corpuscle n * and returns 

to the position it had originally before (he excursion 

one corpuscle maket an oscillation across the din 

the ray and returns the next does likewise, and the next, 

and so indefinitely, After the first corpuscle m wxn St 

another distant from it 186,000 miles will also make a \ibra- 

tion at the end of the first SCCOOd of time in the same straight 


Since these Thomson i an corpuscles are negative and can 
be drawn ottl of their original straight path by the m 
of magnetism, the entire wave motion of the univcr 
electro-magnetic. This, says Larkin, whose description of 
the movement of the oscillating light corpus* vm. 

was prophesied by Maxwell r lts since. The fulfil- 

ment of the prophecy was left to Thomson, There is really 
nu such thing as a ray of light, nor for that matter of pencils 
consisting of a number of rays. The straight line along 
the middle of a wave or set of waves as illustrated by the 
h of the rope is simply to indicate the d irec tion OJ 
the waves, and in a graphic representation it a1s«. m 
to show the amplitude on either side of tlu Frequency of 

the oscillating light corpuscle The amplitude is the 
tance of the sides of the waves from the illustrative 1 1 n- 
tral line of the rav. It repre>cnts the distance of tlu swing 
of the corpuscle on each side of this imaginary straight 
As each wave is 186,000 miles distant from its source 
at the end of one stennd, there must follow variations in the 
length of the waves. Those of the greatest amplitude 
distance of swing of the oscillating lighl corpuscle from 
this straight line, will of necessity be the longest, fewer 
in a centimetre, because of the space required for them to 


Light Energy: Its Manifestations. 

Since Roentgen's discovery in 1896 a host of radiations 
have sprung into prominence, many of which have a relation 
to physiologic processes, and are applicable to therapeutics. 
Among these may be enumerated radiant heat, brush dis- 
charges in vacuum, light, ultra-violet rays, N rays, cathode 
rays, X rays and the alpha, beta and gamma rays of radio- 
active substances. 

These latter will receive especial consideration in a sub- 
sequent chapter devoted to that subject, and their identity 
with rays emanating from other sources set forth. All 
these radiant phenomena are vibrational activities of the all- 
pervading ether and their differences physically, chemically 
and physiologically are due to their varying rates of fre- 

As with electricity so with light. There is an enormous 
range of frequency available. These varying rates of vibra- 
tional activity are not all continuous. In the lack of con- 
tinuity the X ray differs essentially from rays of the con- 
tinuous solar spectrum. 

While it has not yet been proved it is probable that the 
slowest waves which go around the earth are due to the 
electric waves from the sun. Then come what are called 
Langley waves, radiant heat waves, Paschen's waves, and 
waves which get shorter and shorter, the luminous waves, 
i.e., the different colored waves of the spectrum, N rays, 
and, finally, still shorter waves, and at the higher frequencies 
of the ultra-violet region up to the Becquerel or X rays. 

The cathode rays are of a different order, and consist 
of negatively charged particles or corpuscles, as Thomson 
calls them. These are the electrons of Crookes. They move 
with the velocity of from 1-5 to 1-3 that of light. The cor- 
puscle with its charge is identical with the electron. Thom- 
son's corpuscles are positive and negative in electrical 
charge, the positive carriers of electricity being comparable 
in size to ordinary atoms of gross matter, the negative cor- 


puscles flowing between the atoms of all types of matter 
very minute. By their impact against obstacles, the target 
of a Crookes tube, they produce Roentgen rays. Iiccquerel 
rays, discovered by Becquerel in his experiments with ura- 
nium nitrate, were at first supposed to be different from 
Roentgen rays in being capable of polarization and refrac- 
tion. This supposition of ljccqucrel's, both he and others 
subsequently disproved. They arc also identical with the 
penetrable radiations of radio-active substances. All the 
phenomena considered, therefore, may be regarded strictly 
as manifestations of light. 

Radiant Heat. 

Radiant heat, considered in its proper place in its phy- 
sical, physiological, and therapeutic relation, is another 
manifestation of light energy. 

Radiant heat differs essentially from hot air. A ther- 
mometer exposed to radiant heat gives no trustworthy indi- 

Powerful as these rays arc, and sufficient to fuse many 
metals, they can be permitted to enter the eye and break 
upon the retina without producing the least luminous im- 
pression. Gather them in a focus and there is nothing to 
be seen at the place of convergence. With a proper ther- 
mometer it could lx? proved that even the air at the ftxrus 
is just as cold as the surrounding air. The deduction from 
this is that the ether at the focus is practically detached from 
the surrounding air, that the most violent ethereal motion 
may there exist without the least aerial motion, invisible, 
yet the thermal energy is sufficient to raise iron to a tem- 
perature at which it throws off brilliant scintillations. 1 In 
the invisible region below the red, before the swings or 
excursions to and fro of the particle of iron become rapid 
enough to emit dull red. waves are issuing which are too 
long and slow to have effect on the retinal nerves. The 



atoms of some bodies refuse to partake of motion of the 
powerful waves of low refrangibility and, therefore, remain 
unaffected by their heat. Such is not the case of the tis- 
sues of the living organism. Upon it radiant heat exercises 
a profound influence, producing an effect beyond the skin 
by entering the body as a radiant force. Through the large 
superficies acted upon there are sent co-extensive ingoing 
impressions to nervous centres from which they are reflected 
to the various internal organs. 

Langley, with his bolometer or platinum nerve, has in- 
vestigated this end of the spectrum, and his map of the 
infra-red end of the spectrum is 13 times as long as that of 
the visible spectrum. 

The waves or frequencies manifested as radiant heat 
have varying intensities out to the extreme limit. This part 
of the spectrum is full of lines and bands which vary as 
much in width as do those of the visible spectrum. They 
indicate absorption, for absorption is the cause of all dark 
and cold spaces in the solar spectrum. Cold in this part of 
the spectrum corresponds to darkness in the visible. 

The bolometer or platinum nerve shows itself more sen- 
sitive in detecting the long and slow waves beyond the red 
than the eye, just as the fluorescent screen slows down the 
waves beyond the fastest violet or the ultra-violet, rendering 
them visible. The human nerves, to the human sense most 
exquisitely sensitive, are not, therefore, as sensitive as sup- 
posed, for platinum and silver are both more sensitive. 

Brush Discharges. 

There proceed from the sun magnificent waves, one 
oscillation in 6J seconds producing another oscillation. In 
the earth, however, the frequency of an electric oscillation 
is 17 per second. But electric oscillations may be made to 
run up to 50,000 millions per second, while with suitable Ley- 
den jars appropriately connected with a source of E. M. F. 
the frequency may run up'to 30 and 100 millions. Every 
oscillation of the discharge between these jars sends out a 


ugh r 

wave, like a iter, Bui if the tw« 

charging knobs be drawn i 
sufficient potential of ihi> miniature lightning diacl 
break down the air nds into a brush <>f blue light — 

electricity — like the brushes of a paint brush it \\ u 
anted* This discharge, and in nature 

it finds its counterpart in aurora. 1 niliar 

with the phci of this discharge from high let 

from Hottz machines the absolute identity of the 
two phenomeoi is at once apparent " 'The li^ht of the 
aurora, akhou ised by the sun. 

but is caused by the turbulence *e1 up in the earth's 
held bj electro-magnetic upheaval on the sun. The held 
of the earth is tuned for that of the Blffl, iherers in 

sympathetic telegraphy and telephoning. The phenomena 
of the aurora are electrical, affecting magnets and con 
needles on ships/' So also U the brush discharge. In this 
cotmcctaoo this discharge concents us not as it streams from 
the terminal balls of the discharging rods when lb 
longer sufficient potential to cause a disruptive disci, 
nor as it streams from the edges of the insulating plat- 
form nor from wooden balls and points, but when dis- 
charged in vacuo. These tubes when connected bv their 
plat muni terminals to an excited static machine i 
high tension coil glow with supernal radiance. The 
light oscillates with great rapidity. In their behavior 
they have been likened to the oscillating discharges of the 
"aurorae hung up above the poles of the earth/' The 
phenomena occurring in these tubes of varying A 
vacuity "are in that mystical place, the dim borderland bc- 

n radiant energy and radiant matter if indeed thet 
am boundary between, for Thomson's corpuscles and 

ices' electrons, although matter, behave like radiant 

These discharges, electro-magnetic, present then the 
phenomena of light and electricity. They are chemical in 
their action, and the frequencies of the light energy vary 


according to the degree of vacuum. The theory of these 
discharges in vacuum, as well as their physiological and 
therapeutic applications, assume their place in Chapter 

Luminous or Visible Rays. 

Ascending the scale or heating the iron still hotter than 
for the purposes of heat emission only a dull red ap- 
pears. By increasing the heat, there will develop all shades 
of red from a dull to a bright color. If these rays be re- 
flected through a prism upon a white screen a band of red 
light will be seen extending from a deep to a bright red. It 
is not hot enough to emit other than red, that is, its particles 
do not oscillate fast enough to send forth any other lengths 
of waves. If the iron is heated still hotter until it loses its 
red color and becomes white, if reflected through a prism 
upon a screen, a continuous spectrum will be seen. A still 
more intense heat and the color band still complete 
becomes brighter than before. This spectrum is continuous 
because all the frequencies from the long and slow of the 
red on up to the orange, yellow, green, blue, indigo and 
violet, diminishing gradually in length and increasing cor- 
respondingly in frequency, and of gradually diminishing 
amplitude, are present. 

When an inch contains from 36,000 to 61,000 of these 
electro-magnetic undulations their effect upon human sensa- 
tion, by reason of the retina, is that of light. Their num- 
ber compensates for their minuteness. Trillions of them 
enter the eve and hit the retina in the time consumed in the 
utterance of the shortest sentence. 

The shortest violet wave, just before extinction in the 
ultra-violet region, is of such lengths that 61,000 are within 
one inch. As illustrative of the extreme shortness of these 
waves is the fact that the highest musical sound caused by 
an oscillating piano wire 4,000 times per second is conveyed 
by a wave 3 1-3 inches long. All sound waves are, however, 
extremely long as compared with light waves. 


This continuous spectrum has lx*cn likened to the 
keyboard of an organ with every key open, the bellows 
Ixnng in constant action, the bellows corresjxmding to the 
continuous shining of the sun or other sources of white 
light. 1 

The continuous s|>cctrum is very valuable in its physical, 
physiological and therapeutic relations. This is not only 
true of one region or one color, but of the complex of fre- 
quencies of which it is made up. 

Ultra- Violet Rays. 

Bordering on the extreme end of the violet of the con- 
tinuous spectrum is that mystical region, the ultra-violet. 
It has been and is the subject of constant study and interest 
to the physicist, and is constantly being explored with in- 
tense interest. Since the w-rk of Finsen it has Ihvii of 
great prominence in the medical world. The absence of 
strict scientific knowledge of the nature of the inconceivably 
rapid oscillations of the light corpuscles of this region, in- 
visible to the eye save as made visible by a fluorescent 
medium or in their appeal to the imagination, caused results 
obtained from sources of light energy, absolutely barren 
of ultra-violet manifestations, to be attributed to them. 
More, the physiologic phenomena and therapeutic results 
from the use of various sources of light energy have Ihvii 
misinterpreted, and results obtained from the use of light, 
whether from the solar light sifted through a glass lens or 
an incandescent light with a blue glass enclosing bulb, have 
been attributed to ultra-violet light energy, although these 
rays ha\e been absorbed by the int«-rvrning medium of glass 
in both instances, and very fe»-bl\ generated, if at all. in the 
latter instance. The complex of light merg> and its rela- 
tion to therapeutic result, has not been correctly interpreted 
and analvzed. Valuable as are these invisible frequencies. 

'Larkin : Radiant KiuTgy. 


their value is greater when associated with the blue violet of 
the continuous spectrum or its entire radiance. In its ap- 
propriate place, ultra-violet energy receives full considera- 
tion from the physical, physiological and therapeutic points 
of view. The detailed physics of ultra-violet frequencies, 
of unsurpassed interest, as for that matter is the physical 
side of all forms of energy, is taken up in connection with 
their physiologic and therapeutic action in an especial chap- 
ter rather than under the general physics of light energy. 
It is not that ultra-violet frequencies are to be disassociated 
from the spectrum, but quite the contrary. 

By the increased temperature of our illustrative iron the 
excursions to and fro of the oscillating light corpuscles be- 
come faster and faster, and with their increased rapidity the 
amplitude of their swing from side to side is correspondingly 
lessened. The length of the spectrum beyond the measured 
ultra-violet is still unknown, but it seems certain that these 
invisible frequencies become shorter and shorter until they 
are merged into Roentgen waves. 

The N Rays. 

According to the latest report the N rays discovered by 
Blondlot take their place in the violet region of the spec- 

As yet there exists a great deal of scepticism as to their 
existence. They are by no means impossible, they are even 
probable, but they are not yet an established scientific fact. 
It would not be strange if a chemism such as the living 
organism should emit rays of some nature. There is con- 
siderable collateral scientific fact to support this view. 
Suffice it to say if the existence of rays emanating from the 
human body or tissues is proved, it is quite likely that they 
will become of equal if not of greater importance than any 
of the other rays. The discovery, nature and relation of 
these rays to the living organism are considered especially 
in a subsequent chapter. 



Roentgen or X Rays, 

A beam of light which wed through a prism 

bent aside, or refracted. 

To the question why .r benl differently 

when thej strike a piece «'i matter tin .-in 

been given by distinguished pi kes, Lord Kelvin 

and others! h< I the hetcrogeneit) ol matter, M 

is composed of particles or atoms oi molecul* - of infinite 
not incomparable with the In the homo- 

geneity of matter, that ts, with all its parts similar, as is the 
with ether, there would be no such dispersion <>r sorting 
out i^f the waves. They might l>c bent, hut the) would not all 
be bent alike. Dispersion, or separation of thi 
their different sizes depends upon the size and oscillation 
frequency of the atom. The size < ( the 
mated by the amount of dispersion. Were the atoms either 
enormously larger or extremely smaller than light w 
then there would be no dispersion, But If they are at all 
comparable in size, then the waves which are similar to 
them in size are most affected. As the atoms arc much 
smaller than the waves th U effect is upon the blue- 

violet and ultra-violet* They are more nearly in 
pathetic resonance with them, and it IS for this > that 

physically these frequencies are capable of influencing moti 
profoundly molecules or groups Ol molecules in the living 
organism. The longer and slower frequencies, from the 
green down to the infra-red, are much less affected. Until 
the discovery of Roentgen the spectrum was limited by the 

According to Helmholtz' theory of dispersion, the e\ 
ence of still smaller waves Would ultimately give waves 
smaller than atoms. This being the case these waves would 
be bent less, not more, and the result would be a reversal 


*Sir Oliver Lodge: Archives of Roentgen Kay March to June, 


of the dispersion of the upper part of the spectrum. In 
other words, the spectrum would be folded back upon itself, 
and when the infinitely small waves were reached they would 
not be bent at all, but would go straight on. From this 
theory of dispersion it is, therefore, clear that starting at 
the lower end of the spectrum, where the waves are infinitely 
long, the spectrum would double back upon itself until the 
waves would be comparable to an atom in size, so that ulti- 
mately from the shortest possible w r aves there would be no 
bending at all. In the X ray, Helmholz' mathematical 
theory finds its proof. 

They are very rapid, excessively short, smaller in fact 
than anything conceived of before. They are not bent and 
they go straight on. In this going straight on without any 
deviation they are distinctive from the ultra-violet ray. 
Still further, unlike the rhythmic continuous movement 
of light or, in this especial comparative instance, ultra- 
violet light, they are discontinuous, and as yet there is 
no means of rendering them continuous. They are a sin- 
gle solitary ether pulse, up and down almost instantly, and 
then cessation. They may be likened to an energetic 
whip crack, a falling of a brickbat, a jangle, not a har- 
mony coming again and again but infrequently once in 
a thousand years or so in the life of an oscillating ultra- 
violet wave. 

The X ray proceeds from the target with every blow of 
the electron, and in rapid succession as the target is being 
bombarded by the electrons or cathode rays in very large 

In the inconceivably small size of these waves, in their 
suddenness, so to speak, and infrequency, they probably act 
physically to reinstate the vibrations of atomic structures 
in diseases not yet wholly departed from their normal period 
of vibration. 

The property of ionization is possessed in common by 
ultra-violet, cathode and Roentgen rays. 



Cathode Rays. 

In the dark space of a vacuum tube the most inter- 
esting phenomena take place, It is where the cathode 
rays are formed. Those cathode rays are particles of 
electricity shot off from the terminal. They arc 

really the negative corpt:- Thomson. A ray in the 

mind of the pfaysi < tunillv associated with an undu- 

latory motion of the ether. This, says Th is only an 

accidental association, and there is no necessary connei 
between a ray and undulatnry notion. Those negative 
puscles or cathode rays have an extraordinary resemblance to 
the conditions postulated in the corpuscular theory of light, 
travel in straight tines, they are shot off with tremen- 
dous speed, a speed able to carry them about 20.000 mik 
second from the negative terminal f or cathode of a Crookes 
tube. Cathode particles haw <d in a tube hav- 

ing a velocity as much as one-third of light. In their very 
high speed they are comparable only to light. 

Mass of a Negative Corpuscle. — They have but small 
mass weighing much less than an atom. The mass of each 
of these particles is only about one-thousandth part of that 
of the atom of hydrogen, the smallest mass recognized before 
Thomson's discovery. 

Emission of Cathode Rays by Radium, — There are 
some substances which are perpetually emitting cathode 
rays, notably, as was shown by Bccquerel, uranium and its 
compounds, Radium, however, possesses this property to 
an enormously greater extent than excited Crookes tail 

Velocity Greater from Radium. — The velocity with 
which the corpuscles are emitted from radium is about two- 
thirds that of light, and is double the highest velocity which 
Thomson, in his experimental work, was able to obtain in 
exhausted tube excited by the most powerful induction cc 

Phosphorescence Excited by Cathode Rays. — When 
i removed they will infringe on the walls of 
tube and make them phosphorescent. The phosphoresce 


of the glass produced by them is not a unique one, as it is 
shown by many substances. Rock salt becomes a pretty 
violet blue under their influence, and if kept dry, will last a 
long time. Glass is changed by a long exposure and loses 
its power of phosphorescence. In other words, it becomes 
tired, as it were, under the excessive bombardment. 

Thermal Effects Produced by Cathode Rays. — Bodies 
upon which they fall are heated by cathode rays, and if 
concentrated by using a portion of a hollow cylinder or 
spherical shell as a cathode, platinum may be raised to 
incandescence, thin pieces of glass fused and diamond 
charred by them. The energy possessed by the corpuscles 
striking the body Thomson estimates at nearly two calories 
per minute. 

Production of Roentgen Rays by the Impact of Negative 
Corpuscles. — The most widely known property of the 
cathode rays is that of producing the Roentgen rays. They 
arc the parents, so to speak, of the Roentgen rays, for the 
latter are produced whenever the cathode rays strike against 
a solid obstacle. 

By the use of a platinum target in a Crookes tube, the 
cathode rays are stopped and the X rays produced. It is 
not that the cathode rays are reflected, but as every single 
negative corpuscle strikes the target there is emitted by the 
sudden stoppage of the electric charge a single wave. 
"Just as the disturbance made by shaking a whip travels 
down the whiplash, so each of these cathode rays as it stops 
gives an ethereal crack as it were." These "ethereal shells," 
or solitary pulses, arc excited by the impact of the cathode 
rays upon the target, just as sound or heat is caused by the 
impact of the bullet. 1 

Lenard's Experiment ; Transmission of Cathode Rays. — 
Lenard's discovery , just antedating Roentgen's, consisted 

bringing cathode rays outside a vacuum tube. "Before 
le cathode rays could not be used for a therapeutic 



purpose." 1 By facing his vacuum tinV with a vi 
of aluminum foil Lenard succeeded in getting them out. 
These rays arc penetr h to gel into ordinary .or. 

but they arc stop p ed bj ordinar) matter. Aluminum stops 
them less thill any Other solid mailer At the tiffM 
Lenard's discovery, the Strang) ts of these penetr 

aluminum rays received but little attention 

Similar Kffects to Roentgen Rays.— After Roentgen'* 
discovery they came more into prominence, and the efl 
wett found to be precisely similar to the effects of the 
R oentg en rays, with, however, slightly different properties. 
The; are similar in their ( i ) penetrative effects, can go 
through metal; (2) ability to affect photographic pi; 
(3) to discharge Leyden jars; (4) to make gas, through 
which they pass a conductor of electricity; (5) prodtx 
of phosphorescence in substances against which they strike. 

Although capable of producing photographic effects, 
radiographs cannot be produced by them, as the flesh arrests 
them and prevents the showing of the bom - 

Cathode rays outside the tube are, therefore, called 
Lenard*s rays, as he was the first physicist to cross the Rubi- 
con between the inside and the outside of a vacuum tube. 

Thermo- Luminescence Produced by ( atln >de Kays. — 
Cathode rays produce in some substances, discovered by 
Professor EL Wiedemann, a thermo-lumincscence. For ex- 
ample, a mixture of sulphate of calcium with a little sul- 
phate of manganese is not altered in its appearance by the 
rays, but for some time after its exposure it bursts into a 
vivid greenish glow when slightly heated. 

Mechanical Effects Produced by Cathode Rays. — Other 
than the properties possessed in common with the Roentgen 
rays, cathode rays have the property of producing motion 
Of Objects against which they strike This is very prettily 
shown in the experiment due to Sir William Crookes, with 
a tittle mill having a series of vanes, the axle of which is 

*Sir Oliver Lodge. 



mounted on glass rails within the vacuum tube. When the 
discharge passes through the tube the cathode rays strike 
against the upper vanes, and the wheel rotates and travels 
from the negative to the positive end of the tube. At the 
same time, if the vanes are covered with suitable media they 
show a beautiful phosphorescent gleam. 

Electric Charge Carried by Cathode Rays. — Cathode 
rays carry a negative electric charge, and the negative elec- 
trification follows the same course as rays producing phos- 
phorescence on the glass. 

Gas through which Cathode Rays Become a Conductor 
of Electricity. — In their passage through the rarefied gas di 
the tube they change it from an insulator to a conductor of 
electricity as soon as it is traversed by them. The cathode 
rays really constitute an electric current, they are really elec- 
trons in rapid motion. For that matter any electric current 
consists of electrons in rapid motion. They cannot be seen 
as in high vacuum because they are not usually free to move. 
A stream of electrons may be driven down a conductor in 
such a manner as to show that they are producing current. 
This was done by Faraday years ago, who did not know, 
however, what was occurring. As they pass from hand to 
hand, as it were, by the atoms of a metal chain they may be 
likened to a chain of buckets as they are passed along a 
chain of persons at a fire. As they proceed down the whole 
of the matter conveying them can be deflected by a 

The discovery of the true nature of the cathode rays and 
the existence of electrons or particles of electricity, has made 
electric conduction and electric action generally much more 
definite than before. 

Reflection of Cathode Rays. — This is not reflection as 
understood in optics. It is called diffused reflection of the 
cathode rays. When cathode rays strike the surface either 
of a conductor or an insulator, cathode rays start from the 
surface in all directions. All the rays then proceeding from 
a surface struck by cathode rays are called reflected. 

20 limit l.NKkr.Y. 

Magnetic K fleets of ( athodc Kays. — l'y the luminosity 
produced in thi> way their patli. ordinarily a straight line, 
hccomes cur veil when exposed to the action of a mignet. 
A practical application nf this fact is maile in electrical engi- 
neering in the study nf ra pi illy changing magnetic forces. 
Ordinary magnets are t* m i heavy to follow the vagaries of 
the magnetic course, hut the cathode rays, having practically 
mi mass, are ahle to follow the changes in the force no 
matter how rapid they ma\ he. Ily watching the movements 
of the ra\s the hehavior of this course can he deduced. 

Magnetic Spectrum nf ( "athodc I\a\s. When cathode 
rays are produced hy an induction coil which gives a dis- 
continuous discharge the phosphorescence is hroketi up into 
several distinct patches l.\ a miguetic ticld. l ; or example, 
if originally tin -re ; - a narrow -:raight hand of phosphores- 
cence, under the imlneiicc "t" a magnetic field several hright 
hands of phosphtiresceiii'e -t ■] 11 1 .it t ■• 1 h\ dark spaces are 
ohserved. This is :he inaguif.c -jHvtriMii of cathode rays, 
when not produced hy in; chaui-;ns which have a continuous 
K. M. I-"., as an electro Malic machine or a st.irage hattery. 1 

I\e]»nlsi. .ii nf (" Stream. When there are two 
cathode- in a vacuum tuhe c -m:. .ted together, the cat hoi lie 
ra\s from one cathode aw defected when the\ pas< through 
the dark space surrounding the other cathode. This is to 
he explained hy the elect r ■ -static repulsion of the negative 
electricity travelling along the cathode ra\s. hy the strong 
electric field which <iit'r-iiiinN it. 

("analstralileu or Positive l\-i\s. Tin- ( "auaKtrahlen 
were ohserved experimentally when a perforated cathode 
was u.sed. I'mler these condition*, if i-n- pressure was 
hctween certain limits, luminous -:iiams were ohserved 
passing through the holes in she .-a'hodf. tra\ell : ng in 
straight lities an«i emerging on the side ..f the cathode 
remote from the anode 

These excite phosj ,h, in scelice on tl'.e part of the glass 

'Strut!: Phil. Med M:i« . V-.l \I.\III. |. 47*. iSn (Juried 
l»v 'rinuiisiiii. 


upon which they strike. If the glass is soda-glass, sodium 
lines will be observed spectroscopically. When they strike 
a copper plate they oxidize it. This is not due to the impact 
of the rays, but is an indirect effect due to the rays produc- 
ing active oxygen when they pass through the gas. They 
do not exert this reducing effect through hydrogen. The 
Canalstrahlen consist of positively charged particles. 
There is thus a stream of positively charged molecules mov- 
ing toward the cathode, causing this to emit cathode rays. 
When the cathode is perforated a part of the stream passes 
through the holes, producing in the gas behind the cathode 
luminosity, thus forming the Canalstrahlen. This explana- 
tion of Thomson, although not given as sufficiently estab- 
lished, is, however, regarded as the correct one. 

The velocity of the positive ions is very much smaller 
than that of the cathode rays measured, while the propor- 
tion of electric charge to the mass is only about 1/30000 
of the value of a negative ion. It is the same as the vaiue 
of an electric charge to the mass in the ordinary electrolysis 
of solutions. 

The sun, and probably any luminous star, may be re- 
garded as a source of negatively electrified particles which 
stream through the solar and stellar systems. When cor- 
puscles moving at a high speed pass through a gas they make 
it luminous; then when the corpuscles from the sun meet 
the upper region of the earth's atmosphere they will pro- 
duce luminous effects. This is the belief of many astro- 
physicists. If it be assumed that the aurora borealis is 
caused by corpuscles from the sun passing through the upper 
regions of the air, its many periodic variations can be ex- 
plained satisfactorily. 

Alpha, Beta and Gamma Rays. 

In the sensitiveness of the electroscope to radiations of 
many kinds radio-active substances were discovered. These 
are considered at length in their appropriate place. 


The Physics of Light Energy and Radiant Heat. Sunlight, Elec- 
tric Arc Light, Incandescent Light, Mercury Vapor Light, Spark 
and Vacuum Tube Discharges. 

The Physics of Light. 

The purpose of this chapter is to present the physics 
of light as it bears upon its therapeutic uses. It is possible 
that the limit may have been exceeded, and it is probable that 
it falls short of much that the student desires to know. 
These fundamental facts are to be found in every text-book 
on physics with illustrative diagrams, to which the reader is 
directed for further investigation. 1 

The physics of incandescent light, ultra-violet light, and 
fluorescence are considered in detail in the chapters devoted 
to those subjects rather than in this connection. The mer- 
cury vapor lamp gives a powerful chemical light, but owing 
to its size and shape does not lend itself to therapeutic work. 
It is briefly considered, however, at the close of this chapter. 

Analogy between Sound and Light. — The analogy be- 
tween sound and light is a very close one. The inten- 
sity of a sound is greater as the amplitude of the vibration 
of each particle of the air is greater, and the intensity of 
the light is greater as the amplitude of the vibration of 
the air is greater. The shorter the undulations producing 
the sound, the more acute it is, or in other words the more 

x Standard text-books on Physics, Ganot and Daniell. 

24 LltiHT KXICRdY. 

vibrations iherc are to the second. Similarly the color of 
light, or for that matter the invisible waves of light as well, 
is different according to the length of the undulation pro- 
ducing the light. Red light, for example, is due to a com- 
paratively long undulation and corresponds to a deep sound, 
while a violet light is due to a short undulation and corre- 
sponds to an acute sound. 

Perception of Light by the Retina. — The vibrations of 
the frequencies of the s|K»ctruni are perceived by the 
retina only within distinct limits. If a beam of white 
light, from the sun, for example, be transmitted through 
a prism, the light rays are refracted and dispersed, and 
a prismatic spectrum is obtained. White light when 
transmitted through a shutter into a dark room and per- 
mitted to fall on a screen will form a spectrum, assuming 
a definite order, i.e., from the least refrangible red to the 
most refrangible violet. 

White light contains, therefore, all the frequencies of the 
spectrum, the dark or infra-red waves are refracted least, 
and do not act upon the retina, and are, therefore, invisible. 
They act, however, upon sensory nerves, and give rise to the 
sensation of heat. l ; rom Fraunhofcr's line. A, onward, 
the oscillations of light affect the retina in the following 
order and constitute the visible spectrum: red with 481 
billions per second, orange with 53 2. yellow with 503. green 
with 607, blue with 053, indigo with 070. and violet with 
764 billions per second. 

The sensation of color, therefore, depends upon the num- 
ber of vibrations of the light ether, just as the pitch of a 
note depends upon the number of vibrations of the sounding 
body. The number of vibrations for each color is constant. 
There is no color on earth, all colors are in the light, and 
they manifest themselves ns one color or another according 
to the objects upon which they fall. To perceive a color it 
is essetitial that a certain amount of light fall upon the 
retina. At the lowest degree of brightness, blue gives a 
color sensation »vith an amount of light 16 times less than 


required for red. White light of different periods of vibra- 
tion or frequency applied to the eye excites the different sen- 
sations of color, the amplitude of the vibrations, height of 
the waves, or distance of the swing of the oscillating cor- 
puscles from the imaginary line called a ray, determine the 
intensity of the impression of light, just as the loudness of 
a note depends upon the amplitude of the vibrations of the 
sounding body. When all the frequencies fall simulta- 
neously upon the retina, the sensation of white is expe- 

By reuniting the colors of the spectrum obtained by 
prisms white light is again obtained. If none of the vibra- 
tions of light reach the retina, there is what may be termed 
an absence of sensation of light and color, rather than 
blackness. 1 

Light Propagated in a Straight Line. — While the propa- 
gation of light is always regarded as in an absolutely 
straight line in a homogeneous medium, the oscillating 
particles of different rates and length of swing really 
form curves sinusoidal in character, and if, represented 
graphically, a single ray of it could be obtained, would prac- 
tically be that of a sine. The length of the wave is from 
crest to crest. 

The oscillating or swinging corpuscles which represent 
the vibrations of light are at right angles to the hypothetical 
line known as ray. With increasing frequency of these 
oscillations the amplitude of the curves becomes less and the 
waves shorter. For example, in the same length of ray, a 
centimetre, a greater number will be contained. A single 
ray cannot be obtained alone, however, but only pencils con- 
sisting of a number of rays. 

Parallel, Divergent and Convergent Rays. — If these are 
at a great distance from the source of light, and the vibra- 
tions are very small, they will be parallel. This "luminous 
pencil, " or beam, is, therefore, said to be parallel when it is 

'Landois and Stirling, p. 982. 



composed of parallel ra\s; divergent, when the rays separate 
from each other; and convergent, when they tend toward 
the same point. 

The effect of color is produced in the eve by the varying 
Frequencies of the vibrations* For each oolor the number 
of vibrations is constant, but in a given medium the wave 
length differs. 

\ rlucity of Light, — Light moves with such a velocity 
that at the surface of the earth there is, tn ordinary observa- 
tion, no appreciable interval between the occurrence of any 
luminous phenomenon and its perception hv tl 

The Transmission of Ligbi Raya,— Through the free 

ether in a vacuum, and almost equally BO in air, light rays 
are transmitted with equal velocity. The number of vibra- 
tions are. therefore, small or great iti proportion as the waves 
are long or short. 

The velocity of light is estimated at 11)0,000 miles, 
300,000 kilometres per second, or $0,000,000,000 centi- 
metres per second. 1 

The stars nearest the earth are separated fn»m it by at 
lead 306,265 times the distance of the sun; therefore, the 
light which they send requires more than tl rs to 

reach us. 

The visible frequencies are to he found bet ween 763 and 
395 billions per second, quite generally given as 760 to 
billions per sec mid. 

Light Intensity and its Laws, — By intensity of illumina- 
tion is understood the quantity of light received «>n the unit 
of surface. 

The intensity of light is governed by the following laws: 

(t) The intensity of illumination On a given surface 
due to a point surface of light is inverse! v as the square is 
the distance from the source. By doubling the distance the 
strength of the light is diminished to one-fourth. If it be 
increased threefold the strength of light is one-ninth. If 



the distance be increased four times, the strength of this 
source of light must be multiplied by 16 in order to gain an 
equally powerful illumination. 

When the effective light rays strike a surface at right 
angles, the most powerful illumination takes place. 

When the illumination is oblique fewer rays fall on 
the same plane; some of the rays naturally are longer, 
and, therefore, when they strike the plane, they are also 

The brightness of illuminating bodies depends on their 
distance from the source of light, and on their position in 
relation to it as well as upon the intensity of light in each 
single point, and on the size of the illuminating plane. 

(2) The intensity of illumination which is received 
obliquely is proportional to the cosine of the angle which 
the luminous ray makes with the normal to the illuminated 
surface. 1 

It is owing to the divergence of the luminous rays 
emitted from the same source that the intensity of the light 
is inversely as the square of the distance. The illumina- 
tion of a surface placed in a beam of parallel luminous rays 
is the same at all distances in a vacuum. In air and other 
transparent media the intensity of light decreases in con- 
sequence of absorption more rapidly than the square of the 
distance. The law of the cosine applies to rays emitted 
obliquely by a luminous source ; that is, the rays are less in- 
tense in proportion as they are more inclined to the surface 
which emits them. They correspond in this respect to the 
third law of radiant heat. 

Light Standards. — There is no absolute unit of either 
physical or physiological light. There are, however, certain 
standard sources of light, the intensity of whose light is 
taken as unity. (1) The British Standard Sperm Can- 
dle burning at the rate of two grains per minute. 
(2) The Vernon-Harcourt-Pentane Standard, in which 

'Ganot's Physics. 


a gas flame of a given height, observed through an 
opening of definite size, consumes pentane, a variety 
of coal oil. (3) The Carcel Colza-Oil Lamp, burn- 
ing 32 grammes of pure Colza oil jkt hour at a flame 
height of 40 millimetres. (4) The Hefner Altneck Amyl- 
Acetate Lamp, in which the flame stands at an elevation of 
40 millimetres. The latter is generally known as the Ger- 
man unit, the first as the Knglish unit and the third as the 
French unit. There are also the Yiollc Standard Platinum 
Lamp and the Reichsanstalt Standard, the one defending 
upon the light emitted by one square of platinum at the tem- 
perature of solidification and the other upon the light 
emitted from a square centimetre of platinum at a definite 
high temperature. 1 

The eye is not sufficiently accurate to estimate even 
approximately the relative brightness of the illuminating 
planes, or in the event t » f varying intensity of two given 
points from the same source. For this purpose photo- 
meters are used. 

Photometers. — l»y a photometer is understood an appa- 
ratus for measuring the relative illuminating powers of dif- 
ferent sources of light. With the rays falling perpendicu- 
larly upon a unit area, the illuminating power of a source of 
light is the quantity received by the unit area at unit distance 
from the source. 

liunsen's Photometer. — The principle of this photometer 
depends upon the fact that when a grease spot is made on a 
piece of bibulous paper, if the paper be illuminated by a light 
placed in front, the spot appears darker than the surrounding 
space; if, on the contrary, it be illuminated from behind, the 
spot appears light on a dark ground; if the grease spot and 
the rest appear unchanged, the illumination on both sides is 
the same. 

With different light intensities \h\< result is obtained 
bv leaving the one stationarv and nio\ing the other nearer 

Mlmi-iton and Kennel ly : Klrctric Arc Lighting. 


or farther away, when a point will be reached at which the 
grease spot will become invisible because it will then appear 
as bright as the surrounding paper. 

By measuring the distance of the light from the screen 
by means of a scale, their relative illuminating powers are 
respectively as the squares of their distance. 

To make these photometric measurements, light of a cer- 
tain intensity, varying in different countries, as has been 
quoted, is used as a standard. 

Rumford's Photometer. — This consists of a ground- 
glass screen, in front of which is fixed an opaque rod.* The 
lights to be compared, a lamp and a candle, for example, 
are placed at a certain distance in such a manner that 
each projects on the screen a shadow of the rod. These 
shadows are at first of unequal intensity, but by altering 
the position of the lamp, the latter may be so placed 
that the intensity of the two shadows is the same. Then 
since the shadow thrown by the lamp is illuminated by 
the candle, and that thrown by the candle is illuminated by 
the lamp, the illumination of the screen, due to each source 
of light, is the same. The illuminating power of the two 
sources, that is, the illumination which they would give at 
equal distance, is then directly proportional to the squares of 
their distances from the shadows. Or, in other words, if 
the lamp is three times the distance of the candle, its illumi- 
nating power is nine times as great. 

There are quite a number of other photometers with 
which the reader may familiarize himself by reference to 
standard books on physics. 

Measurement of Light by the Actihometer. — In 
the actinometer, an instrument is to be had for the 
measurement of light. That light may be used systemati- 
cally in order to secure a uniformity of usage, precise dosage 
is necessary. 

The principle of the actinometer involves the play of the 
rays of light upon a platino-cyanide of barium screen, and 
then determining the thickness of a solution of ammoniated 



sulphate of copper n to oil off the chemical fre- 


It : of a little Mack chamber in brass 

cubical form. There is a circular orifice on the ant. 
part closed bj of quartz, which permits the entrance 

of tb' and ultra-violet light On the p part 

there is cemented a tube <>f crystal in which gl 
by a rack, a tube of bf «l in its anterior portion by a 

plate of quartz. This plate is covered on the face that looks 
rd the interior half with platino-cyanide and half with 
an absolutely Opaque black varnish, A standard solution <>f 
ammonia- al sulphate i> turned into the apparatus. It this 
actinonieter is directed toward a luminous source, then 
with a convenient thickness of tin absorbent liquid, the 
luminosity of the half the quartz [date covered with plaJ 
cyanide, which had heeoine fluorescent, disapf>ears. 1 
the thickness of the ammoniated sulphate-of-copper solu- 
tion necessarj t<> obtain this result, the chemical paw 
the light source is estimated. 

Superimposed strips of sensitive paper are also used to 
measure chemical light intensity, and observations are taken 

of the progi the photographic effect 

Larscn 1 measured the blackening of chloride-of-silver 
paper as the light passes through. 

By adding certain coloring matters to the bromtde-of- 
silver paper they may be rendered sensitive ' nctes 

of other regions than the blue violet and ultra-violet. This 
is the case with rhodamin, is shown by Andresen, which is 
sensitive to vellow light; the bromide of silver remains very 
sensitive to blue violet, hut this is counteracted by the uM 
of yellow filters. Tin* sensitiveness of Andresen' j rhodamin 
— bromide-of-silver paper, as well as of other papers, was 
proved by Eder in a series of experiments. These showed 
that certain photometer papers are affected by the different 
us of the spectrum, according as they are exposed to a 

Quoted by Freund* 


more or less strong light. It is necessary to take into ac- 
count the concentration and quality of the filtering color 
used to exclude the blue and violet rays — which become 
effective with long exposures. 

Then again there are electric photometers based on a 
peculiar property of selenium. 

As ultra-violet rays favor the formation of an electric 
spark, this property has been utilized for the construction 
of what Larsen, whose device it is, termed an actinoscope. 
The spark of a static machine or a Rhumkorff coil will cross 
a longer spark gap if the negative terminal be exposed to 
ultra-violet energy. 

Reflection. — When a ray of light meets a polished sur- 
face, it is reflected according to the two following laws : l 

I. The angle of reflection is equal to the angle of 

II. The incident and the reflected ray are both in the 
same plane, which is perpendicular to the reflecting 

The light which falls on a rough non-luminous body is 
partly absorbed or transmitted, and the remainder which is 
thrown back on all sides, makes the object visible. With 
smooth polished surfaces, however, mirrors, for example, 
the light is only reflected in certain definite directions. By 
sufficiently smooth is meant a surface the ridges or scratches 
of which are decidedly smaller than the wave lengths of 
light. If they are less than one-quarter of the wave length 
(less than 1/200000 of an inch) they do not cause any 
breaking up of the waves, and optically are considered 
quite smooth. Mirrors are polished by scratching them 
all over with a very fine powder, which makes scratches 
finer than 1/200000 of an inch. The perpendicular pro- 
duced at the point of the reflecting surface where the ray 
impinges is in the same plane as the incident and reflected 
ray, and both form identical angles with it. 

^anot's Physics. 


Mirrors in i n with the use <»f light concern 

therapeutist, as tl »e\ arc used with light m 

■ •ect the light cither < i ) directly tip* n f 

directly upon the surfao 
nude body. The) arc divide 
their shaj ical (concave and c 


Kays of light which diverge Froi 
and fall upon a mirror arc caused eittn to,, or 

to diverge from a second point. In either 
the second point is called the ol the ftrsl point 

Plane Mirrors. — The images of objects in plane mirrors 
an alwajn exactly Opposite the objects, and each 
behind the mirror as the object is in front. The action is dif- 
ferent with curved mirrors, concave and o 

Concave Mirrors. — A concave mirror, spherical shape* 
curved and polished on the inside, may pn 
convergence to a point. Per example, light reflected tif^on 
a concave mirror will converge upon a point in mid air, 
that point is the focus. Were it convex instead of com 
the impingement of light waves upon it and iheir reflection 
WOtdd cause a divergence of the waves. There would no 
longer be a real focus. Light rays falling on a spherically 
curved concave mirror, so as to pass through the centre 
of the sphere, are called axis rays* The spherical centre 
is called the centre of curvature, and the straighl line 
passing through this point and the curve centre of the 
mirror itself is the optical axis of the mirror. 

are reflected back directly. The sun's rays com- 
rom an infinite distance are reflected in such a manner 
that all pass through the focus. This is also the burning 
point. The focus is the point of convergence of all the 
that strike the mirror parallel with the axis. This t 
lies on the main axis, and is midway between the mirrof 
centre and the sphere centre. With the approach of the 
source of light to the mirror, so that its rays are no longer 
parallel to each other, the focus recedes further and further, 


even to infinity. When the source of light is in the focus 
the reflected rays are then parallel. When the source of 
light is brought between the focus and the surface of the 
mirror, they become divergent. 

Parabolic Mirrors. — Parabolic mirrors are concave mir- 
rors whose surface is generated by the revolution of the 
arc of the parabola. All rays after reflection meet in the 
focus of the mirror and conversely, when a source of light 
is placed in the focus, the rays incident to the mirror are 
reflected exactly parallel to the axis. The light thus reflected 
tends to maintain its intensity even at a great distance, as it 
is the divergence of the luminous rays which principally 
weakens the intensity of light. It is because of this property 
that parabolic mirrors are used as projectors in railway 
trains, carriage lamps, etc. 

The Mangin Mirror. — This dioptric reflector is a glass 
mirror of special form. It consists of a spherical mirror 
whose inner and outer surfaces are of different radii. The 
outer surface is silvered so that the rays proceeding from the 
arc pass inward, i.e., to the mirror at the back of the mechan- 
ism before being projected outward as parallel rays. This 
is true of all frequencies of more than 30 micro-centimetres 
in length. Frequencies of shorter length, i.e., the ultra-vio- 
let, do not pass outward through the mirror of glass because 
of their wave length. This is the mirror provided in the 
marine searchlight mechanism, described in another chapter. 

Application of Mirrors. — The application of plane mir- 
rors does not concern us here. Concave mirrors are largely 
used in therapeutic work : ( 1 ) to reflect the light of an arc 
upon a condensing lens; (2) to reflect the sun's rays or the 
light of the arc upon the patient's body. Simple concave 
silvered mirrors are used to reflect the light of the arc in the 
cabinet devoted to therapeutic work. Concave mirrors serve 
to concentrate greater quantities of light than can be done 
with lenses. The mirrors used by Kime for concentrating 
solar light are of this type. Parabolic mirrors absorb but 
little light and can be Utt ' % * suitable focal distances. 



Focal Length. — The point of conve rg ence of the parallel 

rays is the principal i the mirror; its distal 

the mirror is the focal length. 

Refraction, — By refraction is understood the defied 
or bending which the rays of light experience in pas 
obliquely Eroni one medium to another; for example, from 
air into water. If the incident ray is perpendicular to the 
surface, separating the two media, it is not hent hut con- 
tinues its course in a straight line. The incident ray is the 
Olie which strikes the water, and the refracted ray is the ray 
that is hent in the second medium, in this instance, the water. 

The two angles which these rays form, with a line per- 
pendicular to the surface of the water, separating in this 
instance the Iw t o media, the first between the incident ray 
and the line normal to the surface is the angle of incidence, 
and the other formed by the refracting ray and the per- 
pendicular line as it extends into the water, the angle of 

The second medium is more or less refracting than the 
first, according as the refracting ray approaches or de\ 
from the normal. 

All the light which falls on the surface of a refracting 
substance does not pass into it completely, one part is re- 
flected regularly or diffusely, while another penetrates into 
the medium. 

In media which arc uncrystallizcd. such as air, liqui 
ordinary glass, the luminous ray is singly reflected ; but in 
certain crystallized bodies, such as Iceland spar, selenite* 
etc., the incident ray gives rise to two refracted rays. This 
phenomenon is that of double refraction. 

The following law prevails when a luminous ray is re- 
fracted from one medium into another of different refractive 

L Whatever the obliquity of the incident ray, the 
ratio which the sine of the incident angle bears to the sine of 
the angle of refraction is constant for the same media And 
the same colored light, hut varies with different media. 


If the light passes from a rare to a denser medium, the 
reflected ray approaches the perpendicular, otherwise it re- 
cedes from it. In order that refraction may take place, the 
incident ray must form an acute angle with the normal; 
if it form a right angle, it traverses the medium in a straight 
line. Rays impinging at right angles on the dividing sur- 
face of two transparent bodies are more refracted. 

Index of Refraction. — By index of refraction is under- 
stood the ratio between the sines of the incident and refracted 
angles, sometimes spoken of as the refractive index, of the 
second medium with respect to the first. 

The respective index varies with the media ; for example, 
from air to water it is 4-3 and from air to glass it is 
3-2. If the media are considered in an inverse order, that 
is, if light passes from water to air instead of air to water, 
or from glass to air, it follows the same course but in a 
contrary direction. Therefore, the refractive index is re- 
versed; from water to air it is 3-4, and from glass to 
water 2-3. 

The index of refraction of one medium to another on the 
undulatory theory of light is the ratio of velocity with 
which light travels in the second medium to that which it 
travels in the first. For example, the velocity of light in 
glass is 2-3, and in water 3-4 of its velocity in empty space. 
The refractive index depends on the rate of vibrational 
activity of the light corpuscles or its colors. 

The refractive indices of the following substances are 
for D light and at a temperature of 20 . 

Water 1-3333 

Alcohol 1.3616 

Carbon sulphide 1.6276 

a-bromnaphthalene 1.6582 

Ethyl cinnamate at 18.80 1.5607 

Common glass 1.515 — 1.615 

Flint glass 1.614 — 1.762 

Jena, heaviest silicate flint glass No. 557. .. . 1.9625 

Quartz, ordinary ray 1-5442 

Fluorspar 1-4339 

Air O and 760 mm 1.0002922 


Mates with plane parallel nirfio the incident ray 

to be as mii< ml the perpendicular as the 

issuing ray is bent from it; the two ra 
parallel to one Booth* 

Lenses. — These are transparent media, which from the 
curvature of their surfaces have the pft ig ihe 

luminous rays which traverse them either to 

ltc. They vary according to their curvature, and are 
either ip h f ricit , cylindrical, elliptical or parabolic. By a com- 
bination of their spherical surfaces either with c 
with plane surfaces, the number of different lenses is in- 
creased. Of these tlie A mvex, plane convex and 
concave convex are all converging or convex I I hey 
are thicker in the middle than at the edges. Concave lenses 
are thinner in the centre and thicker at the edges. 

In lenses where the surfaces are spherical, the centres for 
these surfaces arc called centres of curvature, and the right 
line which passes through these t\V" centres is the principal 
axis. In or near every lens there is a point called the 
optical centre, which is situated on the axis, and which has 
the property that any luminous ray passing through u <x_ 
periences an angular deviation; that is, the emergent r. 
parallel to the incident ray. 

Ka\s Striking a concave lens parallel with the axis are 
dispersed after refraction- The axial rays passing through 
the centre of the lens are not refraction. 

Objects viewed through a concave lens appear smaller 
and nearer. 

The images formed by different forms of lenses do not 
concern us in this connection. 

Refraction of Sun's Rays in a Double Convex Lens. — 
If the sun's rays be allowed to pass through a lens con- 
vex on both sides, they are refracted 80 as to converge ai 
point of light at a certain distance from the lens, dependent 
upon the focal length of the lens. If a piece <»f paper <«r 
wood be held at this converging point or focus, it will 
become bested and finally Ignite. This is the principle of the 


burning glass referred to under the physics of radiant heat. 
The convex lens acts, therefore, as a burning glass. 

Refraction of Light Rays Parallel with the Axis by Con- 
vex Lenses. — When light rays impinge on a convex lens, 
parallel with the axis of the lens, they are so refracted that 
all of them pass through the focus. 

Focal Rays in Relation to Convex Lenses. — When light 
rays have passed through a focus and then impinge upon a 
convex lens they become after refraction parallel with the 
axis of the lens. The axial rays pass through without 

The Focal Length of a Lens and the Nature of the 
Refractive Index of its Material. — By focal distance is 
understood the distance of the focus from the centre of the 

Both of these factors enter into the construction of lenses 
to be used in connection with sources of light energy in 
therapeutic work. Both are determined mathematically. 
The transparency of quartz to the frequencies of the ultra- 
violet region is dependent upon the nature of its refraction. 

The Effect of Lenses Dependent upon Their Diameter, 
Curve and Refractive Power of Their Substance. — The 
diameter and curve of lenses govern their effect as does 
also the refractive power of the substance from which they 
are cut. For example, glass or quartz. 

Spherical Aberration and Chromatic Aberration. — 
When parallel rays strike a spherical lens close to the 
edge, they do not converge in one focus after reflection, but 
spread over a wider zone, whose axis is the focal line proper. 
The same is true of large spherical mirrors. To this phe- 
nomenon is given the name of spherical aberration. Its 
effect is to blur the image. It is especially prone to occur 
with thick lenses. 

Lenses are also subject to chromatic aberration. As the 
term implies, they break up white light into its component 
parts, as does a prism. If a bundle of rays be thrown on a 
convex lens parallel to the optical axis, the violet rays which 



are refracted at the sharper angles witl intersect each other 
behind the lens at a shorter distance from it than the i 
rays, the longer, slower and V Lftgibte red will inter- 

sect at tli' i point the image 

is caught but one lands out distinctly, all the ol 

are blurred. 

on and Refraction, — Roth of these phenomena 
f concern in the therapeutic uses of light. The imp 
light is not reflected. A part finds its way into the 

lid medium This means that then i rlain U is 

light. The amount of f«>s^ bj reflection depends < n on the 
nature of the m« on the ol the r 

kefrarf en in all its beauty in the diamond, in cut 

glass and in the prismatic pendants from cut glass. 

Transformation of Refracted Light Energy, — All of the 
refracted light does not pass through the second medium. A 
part is used up in it and is converted into other form 
energy; for instance, heat, chemical energy, etc. 

Reflected Light of Less Candle-power than Incident 
* — If the total strength of the light reflected by a body 
and that which passes through it be measured photomet- 
rically, it will be found to be less than that of the impinging 

Prisms in Relation to th> [position of White Light 

— If a beam of light pass through a prism it is diverted 
from its original direction and resolved into its component) 
colors. There appear the colors of the spectrum, red. 
orange, yellow, green, blue, violet. These colors are not of 
sharp definition but merge insensibly into one another. 

Dispersion. — 'Reflection not only changes the direction of 
a ray of light, but if it is not homogeneous, its nature is also 
modified; a ray of light is converted into a rainbow-colored 
band, as may easily be seen by the help of a prism. The 
many colored light rays are transmitted with uniform 

City in a vacuum, but in a denser medium the more 
rapidly vibrating violet rays undergo a greater retards 
than the red rays which vibrate more slowly; the former, 


therefore, are refracted more strongly than the latter. Pas- 
sage through a second prism more strongly refracts the com- 
ponent rays but they are not decomposed any further ; they 
are therefore simple and homogeneous and if combined by 
means of a lens white light is again produced. 

Abnormal Dispersion. — As a rule the refractive index of 
a medium is greater the smaller the wave length of the 
particular light; in the visible spectrum the index steadily 
increases in passing from red to blue. There are substances 
which do not conform to this rule. Their solutions when em- 
ployed as refracting and dispersing agents exhibit the inverse 
relationship between refractive index and dispersion. To 
this phenomenon is given the name of Abnormal Dispersion. 

Luminous, Transparent, Translucent and Opaque Bodies. 
— Bodies are luminous when they emit light, the sun, and 
electric arc and incandescent solid or filament, for example. 

Transparent Bodies. — Bodies which readily transmit 
light, as water, polished glass, gases permitting objects to be 
distinguished through them, are transparent or diaphanous. 

Translucent Bodies. — Those bodies which permit the 
passage of light without the ability to distinguish objects are 
translucent. This is true of ground glass, oil paper, milk, 
blood, etc., and also of the more superficial parts of the living 
organism, such as the ear, hand, and even deeper tissues. 
This translucency of the living tissue, i.e., the blood to light, 
is availed of as an aid to diagnosis. Under all conditions it 
is due to the incorporation of foreign particles from which 
the light is diffusely reflected. 

Opaque Bodies. — Bodies which do not transmit light, as 
wood, metals, are said to be opaque. Their opacity depends 
upon the thickness of their substance. No bodies can be 
said to be opaque, for if cut sufficiently thin, they are all 
more or less translucent. For example, the object glass of a 
telescope thinly silvered is so transparent that the sun may 
he viewed through it without danger to the eye, as the 
metallic surface reflects the sreM*r nart of the radiation 
which falls upon it. jtM Ay can be said 


to be absolutely transparent. There would be no absorption 
in Mich a ea 

Different media transmit different wave lengths. l«>r 

example, glass which is transparent to light is not trans- 
parent to ultra-violet light. 

Physical Condition of the Sun, — As an explanation 
of the occurrence of the dark lines in the soli 
trum, Kircfahofi concluded that the atmosphere of the 
sun encloses a luminous mass which emits a continuous 
spectrum of high illuminating power, This inner por- 
tion i> either solid or liquid, and at a higher temperature than 
the atmosphere. Subsequent and more recent investigations, 
however, show that the sun is much more complex than 
KirehhotT imagined. The nature of the inner nucleus of the 
sun can only be conjectured* as it is beyond the reach of 
observation, In all probability ii consists of a ^as at an 
extremely high temperature, and under such an enormous 
pressure that its properties must resemble tn some extent 
those of a viscous substance, like putty. Surrounding this 
nucleus is the photosphere, composed of glowing cloud-like 
masses of vapor; it forms the visible surface and appears u> 
ipond with the clouds in the terrestrial atmosphere, it 
is unknown whether it is separated from the nucleus by a 
definite surface. Externally; it is sharply but irregularly 
confined, being elevated in BOOM places into facukp, and in 

others depressed, forming spots. The reversing layer fa 
situated directly over the photosphere and produces the 
Frauuhofer lines. Its thickness IS only about 1,000 miles. 
The gases composing the reversing layer are not confined 
exclusively to the surface of the photosphere. They also 
occupy the spaces between the pholosphene clouds and con- 
stitute the atmosphere in which these float. Above the 
reversing layer is the Scarlet red chromosphere, consisting 
of unoondensed gases,— hydrogen and helium. Numerous 
prominences extend from this far beyond the surface of the 
sun. The exterior portion of the sun is termed the corona, 
it consists of clouds and irregular streams of light and 


gradually merges into the surrounding darkness. The 
greater portion of the mass of the sun is within the photo- 
sphere, but the larger part of its volume is outside of it. 
The diameter of the solar atmosphere is at least double that 
of the central portion, and its volume consequently seven 
times as great as this. In the fact that the atmosphere of the 
nucleus of the sun is an atmosphere sufficient to volatilize 
metals, and also that the sun's mean density is low, there is 
found sufficient evidence for the belief that the nucleus of 
the sun consists of gas. As the temperature of the gaseous 
mass is far above its critical point, the high pressure must to exceed water in density, and, therefore, the gases 
must be viscous and comparable in properties with molten 
glass or putty. The photosphere is undoubtedly a gaseous 
envelope, condensed in places into cloud-like masses of vapor 
in consequence of the heat radiating into space. These 
masses account for its irregular appearance, and the solid 
or liquid particles of them cause luminosity and produce a 
continuous spectrum, like the solid particles in an ordinary 

The spectrum of the sun spots exhibits a number of dark 
bands; the dark lines of calcium, iron, titanium, etc., are 
widened, the hydrogen lines are reversed, and the sodium 
lines are also frequently enormously widened and doubly 
reversed. These phenomena render it likely that the in- 
creased absorption is due to gases and vapors rushing in 
to fill a space and absorbing the light emitted from the 
cavity. Lines are sometimes displaced in consequence of 
violent motion of the gases. The faculse show a reversal of 
the H and K bands of calcium, by a thin bright line running 
down the middle of each, and, whilst the reversal over a 
spot is generally "single" the bright line is usually "double" 
in the faculous region surrounding it. From this it is 
thought probable that the faculze are not mere protrusions 
fitg^fj|^^iHlBHh£ re > but luminous masses of calcium 

r atmosphere and possibly identi- 


The emission Bp 
of the Hraunhofcr dark lines, can on!) be observed during 
il eclipse; at the moment when the sun is compl 
red by the moon, Ihc lines of the whole spectrum are 
seen to Rash oat brightly taminom 

The infrequent o ccu rr enc e <d this phenomenon commands 
the attention of A irever he 

ical expeditions journey to the ends ol 
witneai it. 

This flashing spectrum was first Been by Voting: at I 

total eclipse of tht hid in Spain on December jj. [87a The 

had almost hidden the sun, the black lines were still 

v. but at the exact moment when totalit) ■!. be 

saw the black lines disappear and "all at once, as suddenly 

field of 
filled with more numerous bright lines than 
old count." 1 

The- Chromosphere and its Prominences. \ spectro- 
of hi^h dispersive power, the slit widel 
permits a Study of the spectra of the chromosphere 
and a view «.f tin- whole prominence if not too large. The 
prominences appear to bear a certain relationship to tfctt 
sun's spots and facuLe ; they an* divided into two da 
quiescent, cloudlikc, or hydrogen and helium promina 
and eruptive or metallic ones. 1 1 r resemble U 

trial clouds in appearance; the latter are highly lumin 
but the degree of luminosity and the shape change with 
extreme rapidity. Their spe c t r a are vrrv complicated 

The Corona. — Much uncertainty prevails as to the nature 
of the corona. It is only visible during a total eclipse. The 
spectrum presents a double line in the green region 1474 K, 
of wave lengths 5.3 16.87, 

1 kit ol these lines is si to be due to iron as it 

coincides end to end with an absorption black line in the 
spectrum of the sun's Mirface far below. The other does 


not coincide with the line of any mode of matter yet found on 
earth. The substance is named coronium and awaits iden- 
tification. The most plentiful gas in the corona is hydrogen. 
Calcium also is present, and thus far about 30 substances 
have been identified by means of their lines. 

It is now generally admitted that the corona consists of 
an atmosphere extending 300,000 miles and of extreme 

It is as yet uncertain as to the true nature of the coronal 
streamers. 1 They are regarded as a permanent aurora, 
their position and direction being determined by the sun's 
magnetic field of force as the terrestrial field of force direct 
the beams of the aurora borealis ; again they are believed to 
be due to light emitted and reflected from streams of matter 
ejected from the sun by forces acting in general, along lines 
normal to the surface of the sun, and most active near the 
centre of each sun-spot zone. 

Radiant Heat. 

Heat is not transmitted by the intervening air. For 
example, if one stands at a little distance from the fire or 
other source of heat a sensation of warmth is produced. 
This is not due to the temperature of the air, for if a screen 
be interposed the sensation immediately disappears. This 
would not be the case if the surrounding air had a high tem- 
perature. Just so the heat from the sun reaches us, that is 
it is transmitted to the body from the source of heat without 
affecting the temperature of the intervening medium. It is 
said, therefore, to be radiated. Take a hollow glass lens 
through which cold water is allowed to flow in a constant 
stream, and vet the solar rays concentrated by this arrange- 
ment will light a piece of wood placed in focus. Heat is also 
conducted as, for example, when the end of a metal bar is 
heated, a certain increase of temperature is presently ob- 
served J^l^the^b^^ f his discussion of the subject, 



\cr, it U radiant Ihmi which concerns us, the heat 
radiated from the sun or from a source of artificial li 
the ordinary incandescent lamp, for example. 

These bodies, there f< I out rays capable of exciting 

the phenomena of heat, and these heat radiations (invisible 
light rays) penetrate the air without heating it, as 
light through transparent bodies. The terms rays uf heat, 
catoriik rays <«r. as the author prefers, in discussing heat 
from radiant sources, I hernial frequencies, an- used in the 
ray of tight, luminous rays, or visible light fre- 
quencit ->. Bodies ol all temp have the power ol 

radiating heat, nor is it necessary that the) should !*? lumi- 
nous as a fire or red hot hall* From bodies of sufficient tem- 
perature, heat radiations proceed which may he ten 
luminous, from others obscure heat, The brightly glo* 
anthracite fire emits luminous heat rays, i 1 
obscure rays. 

Measurement nf Radiatu Heat.— The pres ! radiant 

heat may be readily detected by the use of Melloni's thermo- 
multtplier, which is a thermopile, connected with a del 
galvanometer. With this apparatus Melloni was able tO 
measure differences of temperature of t/5000 of a degree, 
A more sensitive apparatus is that of C. V. Boy's radio-mi- 
crometer, which enables the detection of differences of tem- 
perature of 1/1000000 of a C.° 

Radiation of heat is governed by the following la 

I. Radiation takes place in all directions from a body. 
It does not matter in what direction in relation to a In 
body a thermometer be placed, a rise in temperature from 
every point is indicated. 

II. In a homogeneous medium, radiation takes place in a 
right line. !f a screen be placed in the right line which 
joins the source of heat and the thermometer, the latter i£ 
not affected But in passing obliquely, however, from one 
medium into another, as from air into glass, the thermal rays 

^Ganot'a Physics, pp. 408, 4091 


or frequencies are deviated the same as luminous rays or 
frequencies. This effect is known as refraction, and is fully 
considered under the head of refraction of light. 

111. Radiant heat is propagated in vacuo as well as in 
air. Fix a thermometer in the bottom of a glass flask, so that 
its bulk occupies the centre of the flask. By the use of the 
blowpipe the neck of the flask is carefully narrowed, and 
by the air pump the interior is exhausted to a proper degree 
of vacuum and then sealed. If the apparatus then be im- 
mersed in hot water, or brought near hot charcoal, the 
mercury in the thermometer at once rises. As glass is a 
bad conductor, the heat rays could not travel so rapidly 
through the sides of the flask and the thermometer, there- 
fore the increase of temperature must be by radiation 
through the vacuum. This phenomenon is daily seen in 
X ray tubes and vacuum tubes excited by electric 

Causes which Modify the Intensity of Radiant Heat. — • 
There is understood by the intensity of radiant heat, at a 
particular place, the quantity of heat received on the unit 
of surface at that place. This intensity may be modified 
by (i) the temperature of the source of heat, (2) its dis- 
tance, and (3) the obliquity of the calorific rays in reference 
to the surface which emits them. These modifications are 
regulated by the following laws : 

I. The intensity of radiant heat is proportioned to the 
temperature of the source. 

II. The intensity is inversely as the square of the dis- 
tance from the source. 

III. The intensity is less the greater the obliquity of the 
rays with respect to the radiating surface. 

The first law is so self-evident as not to need demonstra- 
tion, still if a metal box filled with water at io°, 20 ° or 30 
be placed successively at equal distances from a differential 
thermometer, the temperatures indicated by the latter (5) 

[be in the same ratio as the box ; for example, 
of the thermometer corresponding to the 


I I., I! I 

it to indicates 2°, then that of the others will he 4 
and 6 respectively. 

The sc« Mil. 1 taw fallows from the geometrical principle 
that the surface of a sphere iticn if its 

ratlin a hollow sphere of an) given radius, place 

in the centre, each unit of surface in the 
interim nn: rlain quantity of heat; now it the 

sphere of double the radius be used, a surface four tint. 

will be presented to the 50111 heat? the 

internal surface will therefore, contain four times as many 
units of surface, ami as the quantity of heat emitted is the 
siiitit. each unit of surface will receive one-fourth the 

The third modification is of less general applicahil: 
The intensity is alw; when the radiating rays are 

obltque to the radiating surface than where they are per- 
pendicular. Expressed in mathematical formula, it is 
known as the law of the cosine; i.e., that the intensity of 
oblique ravs is pro po rtional i«« the cosine of the angle which 
rays form with the normal to the surface. This law is 
BO* general, however; it has been known to 1»e true onlj 
Within narrow limits, i.e.. with bodies which, like lampblack, 
are entirely destitute of reflecting power. 

Mobile Equilibrium.— The theory of exchanges sug- 
gested by Prfvost, of Geneva, in regard to radiant heal Is 
QOW generally accepted. All bodies, whatever I heir tern 
perature, constantly radiate heat in all directions. If 
two bodies of different temperatures be placed near one 
another, the one of higher temperature will expen 
a loss of heat through its emitting radiations greater 
1 liti 1 it receives; but the one of lower temperature will 
rise in temperature because it receives an energy 
radiation higher than it emits. Both will ultimately come 
to have the same temperature, but there will still be an 
exchange of heat radiations between them. As the one does 
not receive under these physical conditions more than it 
emits, necessarily an equilibrium of temperature is reached. 


This state is known as that of mobile equilibrium of tem- 

Reflection of Heat. — The thermal frequencies or rays 
which fall upon a body are, generally speaking, divided 
into two portions, one of which penetrates the body 
while the other rebounds or is repelled from the sur- 
face like an elastic ball. This part of the thermal ac- 
tivity is, therefore, reflected, and the reflection of heat 
rays, like those of light, is governed by the two following 
laws : 

I. The angle of reflection is equal to the angle of inci- 

II. Both the incident and the reflected ray are in the 
same plane with the perpendicular to the reflecting sur- 

The absolute reflecting power at an angle of 50 is for 
silver plate 97 , gold 95 , brass 93 , platinum 83°, steel 
82 , zinc 81 °, iron jj° , cast iron 74 . Therefore of the 
baser metals brass first, steel next and zinc third afford when 
polished the best reflecting surface for the lining of an incan- 
descent cabinet for example, where the maximum thermal 
activity is required. Steel would seem to be the most prac- 
tical substance from every point of view. 

Reflection in a Vacuum. — Different conditions obtain in 
vacuo and in the air, the former being cooled or heated by 
radiation alone, the latter by contact with the air according 
as it is cooler or hotter than the radiating body. The quan- 
tity of heat gained or lost in a second is governed by the 
temperature; it is greater according as the difference of 
temperature is greater. 

Burning Mirrors. — From the high temperature produced 
in the foci of concave mirrors, they have been called burning 
mirrors. It is stated that Archimedes burnt the Roman ves- 
sels before Syracuse by means of such mirrors. Buff on con- 
structed burning mirrors of such power as to prove that the 
feat attributed to Archimedes was not impossible. The mir- 
rors were made up of silver plane mirrors about 8 inches 


I, Hll I 

long by 5 inches broad. They could be turned indepen- 
dently of each other in such a manner that the I lectfcd 
from each coincided at the same point. With [28 mirrors 
and a hot summer's sun HufTon ignited a plank of tarred 
wood at a distance of 70 feet. The concavity of the M a 
mirror at the back of the marine searchlight accounts tor 
the extreme heat of the beam of light proceeding from it, 
a temperature much beyond that of arcs of the same 
amperage when : refl ecte d. The power of throwing 
off a greater or less proportion of its incident heat, is knoffl Kl 
as its reflecting power, and it varies with different sub- 
stances. Ol the metals, and also Other substances, taking 
brass as the unit at too, their relative reflecting power is as 
follows : 

Polished brass 100 







Indian ink 



Oili-d glass 



Btll their absolute' reflecting po 
is the relation of the quantity of heat 
reflected to the quantity of heat re- 

The Absorption of Heat — Heat, in common with light, 
is absorbed, and the absorbing power of a body is its 
power which permits a greater or less quantity of the 
heat which falls upon it to pass into its mass. The 
absolute value of the absorbing power is the ratio of 
the quantity of heat absorbed to the quantity of heat 
received. The absorbing power of a body is always in- 
ly as its reflecting surface: a body which is a good 
absorbent is a bad reflector, and via :ersa. The sum of 
the reflected and absorbed heat is always less than the inci- 
dent heat. The latter is divided into three parts: (1) one 
which is absorbed, (2) another which is reflected regularly 
according to the laws for reflection of heat, and {3) whtch 
is irregularly reflected in all directions, and which is called 
scattered or diffused beat. A part of the heat may also pass 
through a substance as light passes through glass. Various 


substances possess varying powers of heat absorption. The 
radiating or emissive power of a body is its capability of 
emitting at the same temperature, and with the same extent 
of surface, greater or less quantities of heat. 

From experimental data the identity of the absorbing 
and radiating power has been determined. 

As they are equal, any cause which affects the one will 
affect the other as well. Whatever increases the reflecting 
power diminishes the radiating and absorbing power, and 
vice versa. These different powers vary with different 
bodies and even in the same bodies, they are modified, for 
example, by the degree of polish in metals. They are also 
modified by the density, the thickness of the radiating sub- 
stance, the obliquity of the incident reflected rays, and lastly, 
by the manner of the source of heat. Metals have the great- 
est reflecting power, lampblack the least. 1 

Vibration of the Particles of a Heated Body. — A 
heated body is to be regarded as one whose particles 
are in a state of vibration, and the higher the temperature 
of the body, the more rapid are these vibrations. A diminu- 
tion in temperature is but a diminution in the rapidity 
of vibration of the particles. The propagation of heat 
through a bar is due to a gradual communication of 
the vibratory motion from the heated part to the rest 
of the bar. The propagation of this motion of heat vibra- 
tions even through the best conductors is comparatively 
slow. There is a difference in different substances, some 
transmitting the vibratory motion from particle to particle 
much more rapidly than others. When a screen is removed 
from before a fire or the clouds drift away from the face of 
the sun, the sensation of heat is instantly perceived. Here 
the heat radiations pass from the one body to the other with- 
out affecting the temperature of the space through which it 
passes. The particles of a heated body being in a state of 
intensely rapid vibration communicate their motion to the 

*Ganot's Physics, sec. 431. p. 419. 


Lir.n t 

ether around tfactn, tin- particles ol which are set in sn 
MVe Vibration and hence give rise to waves in the ether which 
travel through space and pass from run* bod] to another 
with the velocity of light. A ray of heat is merely a series 
of waves moving in a certain direction. In heated bo 
definite wave lengths are emitted according to its 
ture. In other Words, its particles vibrate in a certain period. 
The higher the temperature, the shorter the wave lengths 
and the more frequent because of the more rapid vibrations, 
but they coexist, however, with all those previously emitted 
b\ the same body. The motion is therefore at each sir 
si\e te m pe ra t ure a compound of all preceding ones. The 
carbon filament of an incandescent lamp at a certain tempera- 
ture, dependent upon the E« M. F. and K. of the current 
used, becomes dull red i.e., its particles vibrate at a definite 
period and there is an emission of slow waves of long length. 
Bring it to a brighter glow and there are shorter and more 
frequent waves, while brought to full incandescence means 
still more rapid vibrational activity of the carbon filament 
under excitation by the electric current, and therefore \\ 
still shorter and more frequent, but this latter vibrational 
activity gives not only the shorter and more frequent but all 
the wave lengths which have preceded it. It h a complex 
of the whole. So is the radiant energy of the sun and of the 
electric arc a complex of all the rates ■ >f vibrational activity 
from the lowest to the highest. The optic nerve is insensible 
to a large number of the wave lengths thus produced, appre* 
bending only those that form the visible spectrum. Though 
intense motion may pass through the humors of the eve, yet 
if the undulations of these oscillating corpuscles be tower 
than the red or higher than the violet yet we shall be entirety 
unconscious of the fact, for the optic nerve cannot take up 
and respond to the vibrations which exist beyond the ends <>f 
the visible spectrum, either below the red or above the violet. 
These latter are invisible or obscure rays. 
i u Some flames, that of a Ihinsen burner «t an oxy-hvdro- 
rpiantities of obscure rays, for their 

ten •foilte,; ennt vast qi 
• . .• • • •■ * • •■• . 
* *•• ;. : 


vibrations though capable in part of penetrating the media 
of the eye are incapable of exciting the sensation of light in 
the optic nerve. 

Thermal Analysis of Sunlight. 

The sun as a source of radiant heat concerns us first and 
therefore a thermal analysis of sunlight is called for. 

Let a narrow vertical slit be made in the shutter of a 
dark room and strongly illumined by sunlight and let the 
light from the slit be focused by a rock-salt lens on a screen 
and a rock-salt prism suitably placed. The light as it 
emerges from the prism will be found to present on the 
screen a band of colors in the following order: red, 
orange, yellow, green, blue and violet. This constitutes the 
spectrum, which is more extensively considered under the 
discussion of light. By placing a narrow delicate thermopile 
on the space occupied by each of these colors, it will be found 
to be very little affected on the violet, but a gradual rise of 
temperature will be noted as it passes over the other colors. 
Unconsciously and without any knowledge of this physical 
fact, on the part of the observer, blue and green are spoken 
of as cold colors, while red and orange are universally 
recognized as warm tones. If the pile be moved beyond the 
limits of the luminous or Visible spectrum the temperature 
will gradually rise to a given point where the maximum is 
obtained. From that to another given point the pile indicates 
a decrease in temperature. At that point it ceases to be 
affected. The first point is as far from the second as the 
second from the third ; that is, there is a region in which 
thermal effects are produced extending considerably beyond 
the red end of the spectrum. These rays or frequencies 
represent the different rates of vibration or swing of the 
oscillating corpuscles. In their passage through the prism, 
they are unequally broken or refracted ; those of the longest 
wave length or slowest vibrating period are least bent aside, 
i.e., they are the least refrangible, while the rays of shortest 

wave length* must rapid i period are rlio m 

jtblc In the radian! >f the sun there ts a vast 

of superposed waves of different wave lengths. 
The prism breaks tin* compound waves into theii Cli- 

ents, tlu* short waves being more refrangible than the long* 
ones. All save the red frequencies and those below will be 
considered under the visible spectrum. The evidence of 

istencc ol the rays beyond the violet is obtained by their 
action on silver salts, on fluorescent subi :e. But it 

matters not what the radiation or wave length, if it fall- on 
a lampblack surface, it is absorbed by it and converts 
heat, the al thus measuring the energy of the inci- 

dent radiation. The energy measured in this 
at the red end of the spectrum and beyond, hence the use 
of the term heat rays or thermal frequencies, while in contra- 
distinction, the frequencies are called the light rays 
Of luminous frequencies, while those beyond the violet are 
Spoken of as the actinic rays. There is hut one kind of 
energy radiated from the sun, the heat, light or chemical 
effects depend entirely upon the state or condition of the 
matter upon which the different wave lengths may happen 
to falh Langley, 1 to whom photo-physics is indebted for 
elaborate researches into the previously unknown radiation 
especially at the infra-red end of the visible spectrum, Stafo 
that l 'up to 1872 it was almost universally believed that there 
three different kinds of entities, active, luminous and 

thermal, represented in the spectrum. There is one radiant 
energy which appears to ns as 'actinic/ 'luminous 1 or "ther 
mal* radiation according to the way we observe it. Heat 
and light then, are not things in themselves, but different 
sensations in our own 1 >r different effects in other 

bodies; are merely effects of this mysterious thing we call 
radiant energy/' Over sixty years ago Melloni, an Italian 
physicist, wrote, "Light is merely a series of calorific indica- 
tions, sensible to the organs of Sight, 1 i ice crsa, the radia- 



tions of obscure heat are veritable invisible radiations of 
light." This theory was not adopted until the physical fact 
had been demonstrated by the researches of Langley which 
were much more refined and complex than those of other 
investigators. There is but one radiant energy to the 
modern physicist as unquestionably it will be agreed that 
there is only one matter. 

Chemical action is not confined to frequencies of short 
wave length, any more than thermal action is confined to the 
frequencies of the red region. Under proper conditions the 
green, red and infra-red frequencies will all produce photo- 
graphic action. A proof of the chemical action of the red 
frequencies can be had in the ability to photograph through 
the human body. At least the inference seems fair, for it 
is the red frequencies which pass through. The hand photo- 
graphed by Gebhard had a photographic plate placed in the 
hollow of the palm. It was then imbedded in plaster of 
Paris save for the dorsal surface. After 20 minutes' exposure 
to the light of an electric arc, the plate was subsequently 
removed to the dark room and developed. It was found to 
be darkened and the contours of the hand and fingers were 
distinctly seen, showing that the light had penetrated. Simi- 
lar experiments have been made by Freund, St rebel, Kime, 
Gottheil and others. The only physical distinction to be 
made between light rays, heat rays, and actinic rays is that of 
wave length. And by reason of the different wave lengths 
a difference of physical action upon the living organism 
takes place; it is with different component parts of the 
structure as it is elsewhere in the physical world, the effects 
are those of heat, light, or chemical action according to the 
state or condition of matter upon which the energy from the 
sun or an artificial source is radiated. 

Radiation does not leave the sun either as light or heat 
but as radiant energy. The wave lengths of the radiation 
lying within certain limits fall upon the eye and they are 
called light ; the same wave lengths will decompose the silver 
bromide of a photographic plate and hence they are called 


ir.UT FN 

actinic rays; while equally well will they raise the tempera- 
ture of a blackened bulb th er m o meter, tl they are 
heat rays. Hie short and high frequencies of the vibrational 
activity of the oscillating light corpuscles are the best 
adapted to produce chemical action, which is the highest 
form of vibrational activity. 

prisms of different materials absorb rays of different 
refrangibilitv to unequal extents, the maximum heat will l»e 
found to vary according to the material used. With the 
■-alt we have found it to he in the red, with a prism of 
r it is in the yellow, while with one of crown glass it 
is in the middle of the red. Rock salt however practically 
permits the passage of all the frequencies, even the ultra- 
violet and gives therefore a very normal spectrum. Tyndall 
ed by his experiments that the heating effects gradually 
increased from the violet hut were greatest in the dark space 
beyond the red; the position being about as far from the 
visible red as the latter was from the green, and the total 
extent of the invisible spectrum was found to he twice that 
of the visible. The visible pari of the sun's radiance is only 
a small fraction of the output. 

Langley, to whom we are indebted for the longest wave 
length, devised a very sensitive instrument known as a I Milo- 
meter, 1 or actinic balance, by means of which he explored 
farther and farther into the long heat wave region, using 
prisms of rock salt, because this substance permits the pas- 
sage of more heat than any other known. Professor Lang- 
new bolometer is the most sensitive instrument ever 
constructed. In the Smithsonian report of 1900, appears a 
plate showing the long infra-red or new spectrum, which is 
thirteen times the length of the spectrum which makes im- 
press upon the eve. In it are to be seen wide dark bands 
as in the visible spectrum. They indicate absorption of 
course, as absorption is the cause of all dark and cold spaces 
in the solar spectrum, but it is not known what modes of 
matter caused them. 

'For description sec Ganoi\ Physics. Btc 932, 16th edition. 


In the thermal end of the spectrum are waves of varying 
intensities, showing that the energy of the sun is uneven in 
its distribution. Langley's bolometer detects the lines and 
bands of this end of the spectrum by means of their tempera- 
ture. Cold in the bolometer spectrum has the same signifi- 
cance as darkness in the visible spectrum and these dark lines 
vary greatly in width — just as do those of the visible spec- 
trum. These long slow waves are difficult of recording 
graphically, and are not even comparable in this respect with 
the waves constantly issuing from radium, by means of 
which a much stronger impression is made upon a sensitive 
plate. But as has been shown heat is not confined to this 
region as the frequencies of the visible spectrum also give off 
a great deal of heat, therefore the quantity of light is ex- 
tremely small, and the investigator in his attempt to devise 
a means for artificial illumination deficient in heat is, after 
all, seeking that which nature has not provided in the radiant 
energy of the sun. 

Langley used in his investigations of the heat end of the 
spectrum a Rowland grating 1 so as to avoid effects due to the 
absorption and measured the heat by means of his bolometer 
which showed difference" in temperature of 0.00001 F. 
According to Ganot there was obtained in this way an invisi- 
ble spectrum extending beyond the red to 20 times the length 
of the visible spectrum. The absorption of the radiation by 
the bolometer begins to be measured just outside the violet 
at a wave length of about 0.25/i and is at a maximum at a 
wave length of 0.65 p. The depressions shown in the curve 
represent the dark lines or what is known as Fraunhofer's 
lines. 2 

If a solar spectrum could be produced outside the atmos- 
phere it would probably give a spectrum more like that of 
the electric light, which is unaffected by the atmospheric 
absorption. Flint-glass prisms and especially water will 
absorb the infra or called sometimes the ultra-red radiations. 

'See description, Ganot's Physics, sec. 662. 
'Original paper, Phil. Mag. (V.) Vol. 26, p. 505. 



The absorption in the atmosphere has always been attributed 
to the aqueous vapor, bat according tn Cornu 3 it is ab& 
by th e n and nitrop n of the air. 

The thermal frequencies from bodies heated under incan- 
descence are alt absorbed when the beam is passed ihn 
a solution of alum in water. Rock salt permits 
of h< 'th the luminous and the obscure radiation 
of iodine in carbon bisulphide, which Tyndall Found to be 
impervious to the brightest light, is very pervious to radia- 
tion of great wave length, only a slight absorption b 
Mi> ted hv the bisulphide. This means d in 

determining the relative p r op o rtion of luminous and obscure 
radiations under different conditions, which were found to be 
as follows: 

Source. Lam 

Red hot spin! , , , , o . . . 

Hydrogen it mm 

Oil ll.MS.r 

1 - | 

White hot spiral . . , 

trie light , io 

In medical work, the Battle agents are useful in cutting 
down the obscure radiations or thermal frequencies. A solu- 
tion of alum in water is used for this purpose. Ruck salt, 
which permits th je of the ultra-violet frequen 

permits the passage of all the thermal Frequencies and is 
therefore not 80 good a> quartz in practical work, still by 
having a number of pieces and changing from a warm to a 
cool one. the end can be obtained. 

In India it is the custom to paint goitres with red iodide 
of mercury and then expose the part to the action of sun- 

light Doubtless this is done because of the fact that iodine 

11 save radiation of great wave length. It is a great 

absorber of light. In the authors experience, a e;i>» pj 

goitr d treated by request of the patient, who had 



read largely but not always wisely. A few exposures 
resulted in a very severe dermatitis, infinitely more so than 
had followed the use of the same light source alone. Al- 
though told it would follow upon the treatment, the patient 
discontinued treatment upon its appearance and the ultimate 
outcome in relation to the goitre is not known 

Calorescence. — As Stokes converted the rays of high re- 
frangibility (see Fluorescence, Chapter XX.) into those of 
lower refrangibility and invisibility, so Tyndall increased 
the refrangibility of the infra or ultra-red frequencies 
rendering them visible. This was done by placing the char- 
coal points of an electric-light filament in front of a concave 
silvered glass mirror, concentrating the rays to a focus 
about 6 inches distant. A cell full of a solution of iodine in 
carbon bisulphide, which has the power of stopping all 
luminous frequencies, but gives free passage to the non- 
luminous frequencies, was placed in the path of the beam, 
and a piece of platinum was then placed in the focus of 
the beam thus sifted and raised to incandescence by the 
invisible frequencies. In the same manner, charcoal in 
vacuo was heated to redness. Under a proper arrangement 
of the charcoal points a metal may be raised to whiteness, 
and the light emitted from it on prismatic analysis will yield 
a brilliant luminous spectrum. This luminous spectrum is 
derived entirely from the invisible infra-red spectrum, and 
to this transmutation of the non-luminous frequencies into 
the luminous frequencies Tyndall gave the name of color - 

Tyndall still further showed in these experiments that 
by placing the eye in the focus, guarded by a small hole 
pierced in a metal screen, in order that the converged rays 
should only enter the pupil, and not affect the surrounding 
part of the eye, no sensation of light was produced, nor was 
there scarcely any sensation of heat. A powerful beam un- 
doubtedly reached the retina, although a considerable por- 
tion was absorbed by the humors of the eye, for under 
separate experiment Tyndall showed that about 18 


per cent, of obscure radiation from the electric light passed 
through (he humors of an ox's eye The visual tract 
the optic nerve and the brain, does not seem to be able to 
take cognizance of or r esp o n d to frequencies below the red 
either as light Of heat 

Diathermancy and Athermancy — Transmission of Ther- 
mal Rays. — Diathermancy is the tern* used to express the 
power which bodies have of transmitting heat, and bears the 
same relation to radiant heat that transparency does to light. 
Atl.ennancy. on the other hand, is the term used to exp 
the power of Stopping radiant heat and corresponds to 
opacity for light. 

A tliathcrmanous substance is one which allows incident 
radiation to pass through it, apart from any consideration 
of the wave length of the radiation. A transparent sub- 
stance transmits waves of medium length, and may or may 
be opaque to the very long or very ihorl waves. A 
substance may be absolutely opaque and yet permit the ultra- 
violet or the infra-red or bo*h to pass. By heat rays it is 
the infra-red which are generally understood 

By his experiments Mellon i found that calling the total 
radiation loo there was transmitted as follows: 

Carbon bisulphide 

Olive oil 




Solution of alum or sugar 

Distilled water 

With solids when cut into plates o.t inch thick it was 
found that out of every too ravs 

Rock salt 

Smoky quartz 

Transparent lead carbonate 


At 1 1 in 

Copper sulphate 


A practical application of these tables is to be found in 
the small quantity of thermal frequencies transmitted 
through distilled water, hence the reason for using it pref- 
erably for the water-cooling cylinders of tubes with con- 
densing lenses, as in the Finsen tube; and in the complete 
athermancy of copper sulphate the reason for its use as a 
filter when the solar energy is used for treating skin lesions. 

Tyndall in a series of experiments made to show whether 
there was any relation between diathermancy and transpar- 
ency proved that a layer of water 0.2 of an inch thick ab- 
sorbs 80.7 per cent, of heat from a red hot spiral, and trans- 
mits 19.3 per cent., and that there was no such relation. 

Influence of the Thickness and Nature of Screens. — 
Rock salt transmits all kinds of heat, i.e., from different 
sources, with equal facility, and is the only substance to 
do so. Its analogy may be found in white glass which is 
transparent to white light, no matter what its source. With 
most bodies absorption of heat increases with the thickness, 
although by no means in direct proportion. Rock salt is an 
exception to this rule. The absorption takes place in the 
first layers; the rays which have passed these possess the 
property of passing through other layers in a higher degree, 
so that beyond the first layers the heat transmitted ap- 
proaches a certain constant value. 

Bodies which transmit heat of any kind readily are not 
heated. For example, a window pane is not much heated 
by the strongest sun's heat ; but a glass screen placed before 
a fire stops most of the heat and becomes heated itself 
thereby. So the blue glass screen used in connection with 
the marine searchlight mechanism: The patient exposed 
to the action of the blue frequencies suffers no heat, it is not 
transmitted, but the glass of the screen itself becomes very 
hot, sometimes cracking. 

Absorption by Luminous Heat. — From his experiments 
Franklin found nearly a century ago that the absorption 
of heat by colored clothes increased with the darkness of 
the color. But he used a luminous source of heat, therefore, 



inclusion d for luminous heal With 

ire heat, all clothes were equal!) ab 

The thermal frequencies or heal rays ftibte of 

double polarization and refraction. 

Drj ^<>«. nitro g en and hydrogen are hut little 

absorbent oi radiant beat, their presence being but little 
different from a vacuum. 

Assuming the absorption of dry air to be i, carbonic acid. 
cample, under the same pressure, 30 inches 

The absorption of heal bj aries with the pn 

sure. Tvntlall, in his experiments on the behavior of 
aqueous vapor to radiant heat, showed thai on a daj 

Lge humidity the ah the transparent 

aqueous vapor present in il sphere is 72 times 

as that of the air itself, though in quantity the latter is about 
200 times greater than tin former. He also showed that 
with the sun at heights which are virtually equal there is tire 
smallest transmission of heat on those days <>n which 
the pressure of aqueous vapor is greatest ; that is. when there 
is in<>>t moisture in the atmosphere. In this physical fact 
!s to be found a reason for constructing incandescent 
baths in such a manner as to prevent, if possible, great mois- 
ture of the air of the cabinet from the sudatory action 

Perfumes arc greal absorbers of heat. Tyndall found 
that elementary gases were the feeblest absorbents, while 
of complex constitution were the most powerful. 
Thus it may la* inferred thit absorption is mainly dependent 
upon chemical constitution. Absorption and radiation are. 
therefore, molecular acts independent of the physical con- 
ditions of the body. 

The properties which bodies possess of absorbing, 
emitting and reflecting heat meet with numerous applica- 
tions in the domestic economies and arts. 

Applications.- — As a rule white bodies reflect he*it very 
well, and abeorl little, hut the contrary is true 

of Mack bodies. An exception is to be found in white 


lead, which has'as great absorbing power for non-luminous 
rays as lampblack. Dark cloth, cotton, wool and other 
organic substances when exposed to the action of radiation 
from luminous sources are powerful absorbents. White 
clothing is cooler for summer wear because it reflects by 
reason of the absence of color rather than absorbs the ther- 
mal frequencies of the solar rays. It permits the transmis- 
sion of the chemical rays. Therefore in the tropics where 
the chemical intensity of sunlight is very great, red and 
yellow are worn underneath while white is used for outer 
wear. Polished surfaces emit heat more slowly than dull 

The upper regions of the atmosphere arc cold, notwith- 
standing that they are traversed by intense heat because of 
the diathermancy of dry atmospheric air. The intense heat 
on the top of mountains is undoubtedly due to the com- 
parative absence of aqueous vapor at these elevations. 

The use of glass for shade in gardens to protect plants 
depends partly on the diathermancy of glass for heat from 
luminous rays, and its athermancy for obscure rays. The 
heat from the sun is largely of the former quality, but by 
contact with the earth it is changed into obscure heat, which 
cannot traverse the glass. A considerable part of the solar 
energy is transmitted by water, and bottles of water may 
act as lenses. Accidents might happen in this way, gun- 
powder, for example, be fired while a drop of water on leaves 
in greenhouses might act in the same manner, and to the 
destruction of the leaves. Rock salt coated with lampblack 
or still better with iodine transmits heat, that is, the infra- 
red rays but completely stops luminous heat. Alum 
either as a plate or in solution, or a thin layer of water is 
permeable to light, but stops all the heat from obscure 

This property is made use of in apparatus illuminated by 
the sun's rays, in order to sift the rays of their heating 
power. If desired to avoid too intense heat from an electric 
light thus used a vessel of water or solution of alum is used. 



For example, a Finsen tube on the one hand and a sun 
Of] the other, 

I lie different 901 beftl generally are l l ) mechani- 

cal - comprising friction, perc 

(a) the- physical sources, solar radiation, terrestrial heat, 
molecular action, change of conditions, and el 
<3> the chemical sources or chemical combinations, and 
mure especially o vnbusti< 

Radiant heat as it concerns us hire originates from i i I 
the sun. and (2) from incandescent lamps, There is no 
source of heat so intense as that of the sun. 

Attraction and Repulsion Arising from Radiation. — 
Crookes discovered a very remarkable class of phenomena 

which are due to the radiant action of heated and lump 
bodies. It beautifully illustrates the attraction and repulsion 
arising from radiation ( i I of radiant heat. (2) light visible 
and invisible, (3) cathode rays. A description of it is incor- 
porated in this chapter. 

Crookes' radiometer 1 is a device consisting of a lightly 
I Structure, similar to a wind mill, weighing not more 
than two grains, secured in a glass bulb from which th 
has been mostly exhausted, so as to leave a fairly perfect 
vacuum and which is fused at its proximal end into a : 
tube, and this in turn is secured to a base of wood which 
serves as a support. The vane or By, as it is called, is com- 
posed of tiny discs of mica fastened to four fine aluminum 
are secured in the Centre of the vacuum tube Of 
bulb to a fine steel point which i^ fused into the distal end 
of the bulb. The one side of the mica disc is covered 
with lampblack. When exposed to the action of light OT 
heat, a candle, for example, brought near the fly, the fly is 
attracted and rotates slowly in a direction showing that the 
blackened side moves toward the light. This movement. 
which indicates an attraction, depends upon a certain state 
of rarefaction. The speed of the rotation of the fly gradually 

l Ganot s Physics. 


diminishes in rapidity as the air within the vacuum is still 
further rarefied until a certain point is reached when the fly 
ceases to rotate. Let the rarefaction be pushed beyond the 
point at which, the rotation of attraction ceases and the 
reverse of the phenomenon takes place, viz., repulsion, and 
the blackened vanes move away from the source of light or 
heat. In a double radiometer, in which two flies are pivoted 
independently one over the other, having their blackened 
sides opposite each other, the flies will rotate in opposite 
directions on the approach of a lighted candle. The rotations 
are reversed when a cold body is brought near instead of 
a hot one. The experiments of Crookes and Kundt brought 
to light the very important fact that what had been regarded 
as a complete vacuum, was not in reality and the existence 
of a gaseous residue must be taken into account. The phe- 
nomena are not specially influenced by the nature of the gas, 
for whether the vacuum be one of hydrogen, or aqueous 
vapor, or of iodine vapor there is no material difference in 
the result, save that with hydrogen the exhaustion need not 
be pushed so far as with air. The repulsion takes place with 
all the rays of the spectrum, the intensity diminishing from 
the ultra or infra-red to the ultra-violet. The interposition 
of a plate of alum, when the chemical frequencies, violet and 
ultra-violet, are active, has no effect upon the phenomena, 
but a solution of iodine in carbon bisulphide diminishes the 
repulsion. The rapidity of rotation depends upon the inten- 
sity of the source of light. A strong light causes so rapid a 
rotation as to prevent determination of the rate of speed. 
Two candles, for example, placed at the same distance will 
secure double the speed of one. When two different sources 
of light are placed successively at the same distance, and 
produce the same rate of rotation, then their intensity is 
equal. If. when placed at different distances they produce 
the same speed of rotation, their intensities are directly as 
the squares of these densities from the radiometer. This is 
the principle which governs the use of the instrument as a 
photometer, for comparing and measuring different sources 


LU.JI I I MkliV, 

of light. lornparato of the intcnsit 

light ma) also he made h> a Crookej radi d the 

distribution of in the solar spectrum investigated by 

its means. 

When the pressure lias not been reduced beyond a 
point, Lc, afl kmg as the apparatus still contains air, it i 
difficult r<> explain the phenomena of attraction observe 
the experiments by tfie action of convection curren 

Heat falling upon the blackened disc will rai^e its b 
perature, and the temperature of a layer of air in im 
contact with the disc, would also be raised. This \ 

it to expand and rise, flowing over the space behind 

Use, then Ig the pressure there. The repul- 

sion observed, however, at a higher degree of vacuum is due 
to a reaction behind tlte vane and the l:1 iss envelope, and is 

ace an illustration and a proof of the modern views a 
to the constitution of gases. The general nature of this 
theor) is that jiras is an assemhla^e of independent moled 
which are perfectly elastic, and which move wirh g 
rapidity ; the pressure is caused by their impact against the 
side of th in which die gas is contained. The equal 

transmission erf prcSStl ffectcd hv the impact 

of the mol st each other. The mechanical effect 

of the force of repulsion is calculated by Crookes t<» he e«pial 
to about the i/ioo of a milligramme on a square centimetre 
This force is sufficient to account for the effects observed 
hv reference to admitted principles of the mechanic d tin 

ases (Stone) I. The light vibrations pass through the 
thin ^lass, without raisin mperature, ami falling OH 

the blackened side of the vane is absorbed by it. In conse- 
quence thereof it Incomes slightly hotter. The layer of 
extremely rarefied air in its immediate contact with the 
blackened disc will also become somewhat hotter, and the 
molecules will fly from the disc with greater velocity. 1 
more rapid motions would be equalized h\ their impacts 

*For Convection Currents, see pp. 104, 414, Ganot Physics, 16th 


against other molecules and a uniformity of pressure, i.e., of 
temperature would be established under ordinary pressures 
or even at moderate degrees of rarefaction. With the in- 
crease of rarefaction, however, the frequency of these inter- 
molecular shocks diminishes rapidly and in consequence a 
great number of the molecules, after having been heated by 
contact with the blackened sides of the palette, will strike 
against the cold glass. The effect of this will be to cool these 
molecules, that is, to diminish their velocity, and it will be 
this kind of molecules chiefly which will fall on the back of 
the disc and on the regions behind it. An excess of force 
equal and opposite to that on the glass acts against the front 
of the disc and accounts for the phenomenon exhibited by 
Crookes. Therefore, other things being equal a fly will 
rotate more rapidly in a small than a large bulb. 

Spectrum Analysis. — Spectrum analysis is a chemico- 
analytical method by means of which it is possible to deter- 
mine the constituents of a substance by observing the refrac- 
tion (dispersion) or the diffraction of light rays. 1 It also 
offers an opportunity of investigating the molecular struc- 
ture of matter. When light rays are refracted the image 
produced is termed a spectrum. Rays of all refrangibility 
are emitted by white hot bodies and form what is termed a 
continuous spectrum, Plate i. On the other hand, glowing 
gases of vapors emit rays of definite refrangibility. The 
spectrum of these is a discontinuous one consisting of bright 
lines which are characteristic of each substance. These 
characteristic lines serve for the identification of given sub- 
stances whether they exist singly or in connection with other 
bodies. In this way the constituents of the sun are known, 
as the solar spectrum with its many colors and shades of 
coloring is the written or pictured evidence of the nature of 
its molten matter. 

In the passage of rays from a white hot solid through a 
colored medium, some of them are retained and give an 

'Ganot's Physics, 16th edition. 



absorption spectrum. This varies with ihc chemical cot 
sit ion of the medium. By reason of the 
characteristic of spectra reactions, their employment has 
to the discovery ol a Dumber oi new elements which occur 
in small quantities only. The distance from the IOUT0 
light has little effect on the spectrum, therefore, it i> sue- 

Fully employed for the investigation of celestial bodies, 
extending a knowledge of them not dreamed of and unat- 
tainable in any other wav 

In common with all scientific development, the hist 
of spectrum analysis is one of exceeding interest, and both 
for an epitomized historic sketch as well as complete spe 
trum analysis, the reader is referred to Landauer's work, 1 
and also Watts' Index of Spectra. 1 Spectrum analysis was 
founded by Kirchhoff and Ihiusen in 1859. 

Spectra are obtained by means of j 1 1 prisms and (2 
means of gratings. There are two kinds of gratings made* 
the one <>i" glass, which is transparent, and the other of specu- 
lum metal The latter is the one most commonly used in 
spectroscopic work as it absorbs less light than the glass. 
The most complete gratings are Rowland's. His plane and 
concave gratings with from 10,000, 14438 and 20,000 lines 
per inch are almost faultless and comparatively free from 
scratches caused by irregularity of the diamond point 

Diffraction. — The production of spectra by means of 
gratings is due to diffraction ; part of the light traversing the 
spaces between the rulings continues in a straight line, but h 
portion is bent sideways or refracted by the edges of the 
opaque parts. 

The wave theory of light permits of the following expla- 
nation of this phenomenon; The light waves which fall on 
a fine s!it cause the particles of ether present to vibrate; this 
motion is communicated to the neighboring particles and 
produces an equal number of light waves, which reinforce, 
weaken or neutralize each other, in accordance with the law 

'Spectrum Analysts, John Lamftuer, 
*Watu" Index of Spectra* 


of interference. This neutralization occurs in all directions, 
in which the difference between the two sets of waves is 
other than a whole wave length. The image of the slit in the 
middle in white light diffracted by a grating is white, be- 
cause at this point all the colors are superposed, but the 
color waves which differ by one wave length collect at 
each side according to their wave lengths, and form a spec- 
trum of the first order ; these rays with a greater difference 
of phase forming the spectra of the second, third .... mth 

When the distance between the lines of the grating is 
known the wave lengths are determined by measuring the 
angle of diffraction with a gonimetre. 

In this way the following values in ten millionths of a 
millimetre for the Fraunhofer lines of the spectrum were 
obtained. (See colored plate.) 

The wave lengths are given in Angstroms : 










5890.18 Sodium Lines. 













The wave length \ (i) is determined by dividing the 
velocity (v) (2) by the frequency. The wave length of the 
extremity of the visible red found at the lower end of the 
spectrum, is for the A-line .000076, that of the yellow D-line 
.0000589, and that of the K-line at the limit of the visible 
violet, .000039 mm. The velocity of light is known to be 
about 300,000 kilometres per second. 

Given the velocity and the frequency, the number of the 

vibrations (;i) can be obtained by the formula // = ^. 


i.N, lit EN 

These are two n units of wave lengths smaller than 

tin millimetre, By reason of the magnitude of the figures 
when the millimetre is used, il is much more simple u> use 

the unit adopted for the measurement of wave length in a 
vacuum, the millionth part of a millimetre — o.ooi micron 
lhts unit is represented b) the symbol *w. One-tenth 
part of this, equivalent to I/IOOOOOO of a millimetre 
is known strom's unit As visible radiation is from 

.000077 to .000039 millimetre, its equivalent in microns is 
from 0.77 to 0.39 micron or 7.700 to 3,900 A 01 Angstroms ' 

These numbers are inconceivably great* therefore it is 
usual to define the color b) tfae wave length, although this 
varies with the medium 

Listing's scale i> used for the classification of lines of the 
spectrum, according to color, it runs as folic 

.*.. to 7230 Infra-red 5850 to S?S° fdtaw 

4540 to 4J4O im! - 
7230 " 6470 retl 5750 M 4920 green 

424O to IQ70 I 1 "let. 
6470 5850 orange 5920 to 4550 Hue. 

3970 to - . . . ultra-violet. 

The most readily recognized lines in the spectrum arc 
from A to II The eye is most sensitive to the light between 
D and Ej that is, a part of the yellow, The light becomes 
less and less visible from that point toward either end. until 
the red rays beyond A and the ultra-violet hevond H are 
hardly distinguishable 

The solar spectrum is crossed by thousands of black lines 
known as Kraunhofer's lines, from the name of the dis- 
coverer, scattered here and there in Ihe mulsi of the brilliant 
and gorgeous colors of the spectrum Everv phase of 
matter Known casts lines in the spectrum which are bright 
and highly colored, not black t )r in other word- each 
phase of matter, when corpuscles are torn apart and sep- 
arated widely enough to allow theni to oscillate, vibrates at 

dauer 5p< ctrutn \nalj si - m> ii< ** 


its own definite rate. The oscillation of each corpuscle will 
cause another to swing, and another, the motion being in 
a wave movement. But each wave strikes its own place in 
the spectrum and the bright lines in the spectrum are formed 
by sets of the similar waves, due entirely to their wave 
length and rates of oscillation These appear in the solar 
spectrum as a result of the intense heat acting upon the 
different substances of which the sun is composed. Artifi- 
cially, there is to be had in the electric arc a similar source 
of energy, and by placing in the crater of the positive carbon 
different substances for volatilization, or forming the elec- 
trodes of them as with carbon, they are torn apart by the 
intense heat and their corpuscles are made to swing at their 
own rate. The instant the gas becomes hotter than white 
is the instant when each corpuscle is torn away from all the 
others, to vibrate at its own rate. And as the corpuscles 
swing or oscillate one after another to form a wave they take 
a definite place in the spectrum, easily determined by means 
of a spectroscope. 

They may each one be regarded as a letter in nature's 
alphabet Their positions are measured with accuracy, and 
waves sent from iron, oxygen, sodium, titanium, helium, 
potassium, no matter what the substance, fall absolutely into 
their own and a definite place in the spectrum. 

The Visible Spectrum. — Only the small portion of the 
spectrum between wave lengths 400^/*, and 760/iw is, in 
ordinary circumstances, visible to the eye, but the part be- 
yond 800 /*/* becomes visible if the shorter waves are cut off, 
by means of a dark red glass, whilst those far beyond the 
4cxw* are seen if the longer waves are eliminated. 

The Invisible Spectrum. — The region beyond 760^/i is 
termed the infra-red, while that below 400 w forms the 
ultra-violet. In the former Langley reached a wave length 
of 5300*/* and Rubens one of 575//U. 

The infra-red rays may be detected by their thermal and 
photo-chemical properties and also by means of phosphores- 
cence. See page 76. For the investigation of this region 



Langley's actinic balance or bolometer is employed; 

its means a rise m temperature of o.i ay be 


Langley's Bolometer. — This consists of a Wheatstooe 
bridge, the arms being formed of two extremely thin black - 
ened wires of equal resistance; if the temperature of one 
changes, the equilibrium IS disturbed and the galvanometer 


i hemical Action of the Red and Infra-Red Rays. — 
I ' »r a long time it was supposed that this part of the 
spectrum was incapable of chemical action. Becquerel, how- 
ever, observed that I be red rays affect stiver chloride, which 
has been previously exposed to light for a short time. 
Draper succeeded in photographing the beginning of the 
infra-red spectrum, but it was not until Abney prepared a 
special bromo-silver emulsion — sensitive to the infra-red — 
that complete photographs were produced He has obtained 
photographs of the solar spectrum up to wave lengths of 
2/OOii/i. both with a prism and a grating, and also photo- 
graphed a number of absorption spectra, 1 The most com* 
plete photograph of this region is due to Langley; however. 

The ultra-violet region in the solar spectrum does not 
extend beyond aboitt 300 microns With an increase of 
temperature the Spectra tend to develop into the violet. 
Hence, on account of the extremely high temperature of the 
sun, a considerable portion of its spectrum must necessarily 

]t< observation. Jn this connection the reader is referred 
to Chapter XVI. Suffice to say here that according to Lang- 
ley 2 it would take nearly ion feel of map to depict on a 
prismatic scale the spectrum of the ultra-violet region, 
though it is caused by but a small fraction of the sun's 
energy, si. monstrous is the exaggeration due to dispersion 
hi the prism. It really contains much less than the one- 
hundredth part of the total solar energy which exists the 
visible spectrum containing perhaps one-fifth the energy of 

'Landauer: Spectrum Analysis. 
*Langk-> : SunthM>ni;in Report!, p '^4 

THE physics Of LIGHT ENBRG v. 71 

the sun." The length of t!ie spectrum beyond the violet is 
stilt unknown, the researches of Schumann giving the 
shortest wave length yet recorded photographically, the only 

means available fur the chemical end ol the spectrum other 

than their fluorescing properties, and its wave length is (200 

niiiis. The lengths of the waves produced by the oscillating 

corpuscles of this region are extremeh short, and it is sup- 
posed that they continue to become shorter until they become 
elect To-magnetic Roentgen waves l 

Iron vibrates at many different rates and its spectrum is 
the richest in lines; tliev are distributed OVCf cverv part of 
the field. It heats with 480 different velocities 

Kayser and Runge* measured more than 4500 lines, and 
on comparing them with Rowland's solar atlas between 
5?of//i and 320^1, they were unable with certainty to detect 
a single line which does DOt appear in the solar spectrum, 
(urnn photographed the more prominent lines in the ultra- 
violet, i.e., between 410^/* and 2Qcftp, This region was ex- 
tended by Lievmg and Dcwar between Jo : v > \Ofif*. 
It is because of the arc spectra of iron that it is valuable 

If the length of the light spectrum be placed at one, that 
of the heat spectrum is 13, while that of the chemical is 

Fraunhofer or Black Lines of the Spectrum. — 
Fraunhofer in 1824 observed the coincidence of these so- 
dium lines with the double D-lincs of the solar spectrum. 
In his study of absorption spectra Kirchhoff proved the na- 
ture and origin of these delicate dark parallel lines which 
web themselves across the solar spectrum, Fraunhofer dis- 
covered them by the use of a telescope. KirchhofT explained 
the reason for their existence. If two waves, formed by the 
oscillations of their light corpuscles, exactly alike, interfere, 
both are totally destroyed. 

Illustratiflhcf tne Interference of Waves. — Let two 


be dropped in water at some distances apart The 
to which they give rise will expand in circles; in a 
short lime the two circles will collide ; but if two waves in . p- 
|h tsite phase meet, the water will be at rest and a cork floating 
thereon will not oscillate. It is a principle of wave motion 
that waves interfere. If two water waves interfere, rcM suc- 
ceeds: if two light waves darkness. Therefore, ooftcl 
Larktn* whose simile is used, soilness in water corresponds 
to darkness in the midst of light, for light added to light may 

produce darkness. 

Take sodium, for example. When sodium is heated hoi 
enough to be torn apart, either in a Bunsen burner or by 
the electric arc or spark, two bright yellow lines will Hash 

out, and all the other portions of the spectrum will be black. 

This is because the metal sodium can only vibrate at tWO 
that is, it can only be torn into corpuscles at these two 
rates, ami, therefore, the whole of the spectrum other than 
these two \ellow lines is black. The metal sodium, the 
basis of Gammon salt, is omnipresent, for the ocean spraj as 
it evaporates in the air leaves minute particles of salt in 
suspension. As little as 14 rnilliooths of a milligram of 
sodium is sufficient to project the well-known sodium lines. 
The rustling of a paper, or movement of a hand through the 
air is sufficient to arouse a hurricane of these particles. In 
the act of examining the spectra of ;\n\ given substance 
they fall into the source of heat, are instantly torn into cor- 
puscles hundreds of millions of times smaller; and theft 
up their own waves which enter the slit. 

If a strong white light concentrated into a beam be 
sent from an electric arc, through the flame in which the 
sodium has been torn apart the bright yellow lines will 
vanish, and all the other parts of the spectrum appear, save 
in the tWO places occupied b> the bright sodium lines, which 
n<«w, however, arc black. 

If, instead Of the arc light, sunlight be sent through the 
yellow Same the two black lines in the yellow region of the 
solar spectrum become blacker than before. The corpuscles 


of sodium can only oscillate at the two rates and at no other. 
Therefore the yellow flame lets every other color rate 
due to oscillating light energy through without hindrance, 
and absorbs the yellow producing the black lines. This 
discovery of the fact that the black lines were due to absorp- 
tion led to the formation of the following law by KirchhofT : 

All modes of matter when vibrating at their own rates 
absorb the same waves they are able to generate. 

Since the solar spectrum has dark lines where sodium, 
iron, etc., give bright ones (see frontispiece), it is assumed 
that around the solid, or more probably the liquid body of 
the sun which throws out the light, there exists a vaporous 
envelope which, like the sodium flame of the illustrative 
experiment, absorbs certain rays, namely, those which the 
envelope itself emits. Therefore those parts of the spec- 
trum which, but for this absorption, would have been illumi- 
nated by those particular rays, appear feebly luminous in 
comparison with the other parts, since they are illuminated 
only by the light emitted by the envelope and not by the 
solar nucleus ; at the same time the conclusion is forced that 
in this vapor there exist the metals sodium, iron, etc. Each 
condition of matter when its corpuscles are vibrating at 
their own characteristic rate causes different sets of waves, 
varying in length, amplitudes and periods of oscillations. 
All the 80 or more modes of matter which the analytical 
spectroscopist has caused to vibrate in front of the slit of 
the spectroscope by heat, as in the electric arc between carbon 
terminals into whose positive crater metals were placed, 
cast in their respective spectra the same lines as those found 
in the solar spectrum, demonstrating their presence in the 
gaseous envelope. 

Absorption Spectra. 

The absorption spectrum of a substance corresponds 
with its emission spectrum at the same temperature and in 
tjie same molecular condition. 



This law. the law was establisl 

Kirchhoff in 1850, as 1 result of his study of al>^ 
spectra, viz.. the relationship between emissive and abeorp- 
tive power of all suhstauo > Eof light of the same V 

The fact that reflected light is of less candle-power than 
the impinging light leads up to one of the most intercs 
and important phenomenon in light physics, and one that is 
especially valuable in its physiological relation, viz., 
of absorption. 

Ab s orp tio n of tight energj does not mean its loss; on the 
contrary, whenever and wherever the phenomenon of absorp- 
tion is observed, there is work done. Throughout the sub- 
sequent chapters of this volume, it is referred to again and 
again as of great importance, \<> en erg) is lost. Tin 
according to the law of conservation of energy. The 
tmction of energ) in space or its absorption and consequent 
disappearance in matter is one of nature's fundamental 
truths. When absorbed, it is converted into other forms of 
energy of equal value. When the waves of light fall up m 
a growing plant, for example, they do work. They are 
to be absorbed, and the green leaf absorbs all the frequen 
of light energy <ave the green which are reflected. Tn the 
light-absorbing substance a transformation takes place, 
beautifully shown in the green leaf by the chlorophyll func- 
tion. In the appropriation and selection of waves by mat- 
ter, whatever its nature, the light is sensibly weakened, as 
in passing through the substance a part of its energy has 
been absorbed. 

Even black Hue in the solar spectrum is an absorption 
letter, by means of which the waves that are absent may be 

Absorption spectra are usually observed at low tempera- 

Fluorescence and Absorption.— The phenomena of phos- 
phorescence and fluorescence are associated with absorption 
of light. 


Certain substances become luminous by the action of 
light ; if the luminosity ceases upon the withdrawal of light 
they are said to be fluorescent (see Fluorescence, Chapter 
XVI.), whilst the term phosphorescent is applied to sub- 
stances which continue to be luminous after the light is cut 
off. In accordance with the law of conservation of energy, 
the rays causing these phenomena are absorbed, fluorescent 
bodies exhibit corresponding absorption spectra, and as 
they absorb the ultra-violet more or less completely, they 
all fluoresce in this region of the spectrum. 

Phosphorescence. — Under the name of phosphorogenic 
rays Becquerel has described the rays given by phosphores- 
cent substances. 

These are rays which have the property of rendering 
certain objects luminous in the dark after they have been 
exposed for some time to the light. This is a species of 
luminosity very closely allied to fluorescence. Indeed, ac- 
cording to Becquerel, who discovered this property in lumi- 
nous rays, fluorescence is only phosphorescence of very short 
duration. He distinguishes between the rays which origi- 
nated the luminosity, the exciting rays, and the continuing 
rays to which he gave the name of phosphorogenic rays. 

In fluorescent bodies the radiation exists only during the 
time the body is exposed to the exciting rays of light. In 
phosphorescent bodies, however, the radiation persists after 
the exciting cause is withdrawn. Among some of the 
natural and artificial substances which have the quality of 
phosphorescence may be mentioned diamonds, calcareous 
spar and sulphide of calcium. The latter is the best and 
most brightly phosphorescent substance known up to 
now. It is called after its discoverer, "Balmain's Luminous 

Artificial phosphorescent bodies include the sulphides of 
the alkali earths, which are obtained by heating sulphur with 
limestone, barytes or strontium salts. 

Color of Phosphorescent Light. — The colors of phos- 
phorescent light depend not only upon the chemical constitu- 


lk;ht energy. 

don of the substances which emit them* but also upon 
physical nature and temperature. 

Intensity of li scent Light. — The intensity of 

phosphorescent light is increase*! by heating. The \\ 
of phosphorescent light, as those of fluorescent light, arc 
of greater length than the exciting light. There is eoctstd- 
erahli ice to indicate that in phosphorescent light 

energy is given off. which has been taken from the absorbeel 
light of the exciting light BOUTCe. This is in accord with 
physical laws, for absorption means work done or em 
imparted. Phosphorescent light always has a far wes 
light than the light acting to produce the phosphorescence. 
It has heen calculated that the light of the best and most 
brightly shining phosphorescent substances excited by day* 
tight, when in immediate contact with bromide-of-sih 
tin plate, arts about as powerfully as the light of 0OC norma) 
candle at 50 centimetres distant. 

Phosphorescent Light Renders Visible the Tnfra-Red 
Spcctrun. — Hectpierel and Seeheck discovered that yellow 
and red rays counteract the action of the violet rays, in nther 
words, extinguishing or at any rate considerably weakening; 
the brightness produced by them. 

As fluorescent plates or the substances are used to render 
visible the ultra-violet spectrum (see Chapter XVI.). so 
phosphorescent plates were used by Becquerel to make the 
infra-red visible. For example, if a plate covered with btal- 
main's luminous color, which has been exposed to daylight, 
and is, therefore, luminous, is then exposed to the infra-red 
spectrum, i.e., the dark, at first the spectrum 1 rinds become 
brighter, the Fraunhofer lines remaining unaltered. This 
soon changes and the Fraunhofer lines gain in luminosity 
until they appear bright on a dark ground. 

Duration of phosphorescent Light. — This varies with 
different bodies. There is no connection between the inten- 
sity of the phosphorescent light and the duration of the 

Absorbed Light, the Action of. — From a study of the 


physical effects of light we find that absorption is a most 
important phenomenon of light energy. The appropriation 
and selection of waves by matter and their eventual return 
to space constitutes the life of the universe. None of this 
absorbed light is lost. 

Heating Effects and Calorescence. — (i) It is trans- 
formed into heat; the rays which fall upon a body heat it 
and are emitted as obscure heat rays of greater wave length, 
the reverse of which is true. The body upon which obscure 
heat rays fall may be heated till it shines. To this phenome- 
non Tyndall gave the name of Calorescence. 

Fluorescence. — (2) In certain substances absorbed light 
causes the immediate emission of new light rays of different 
colors. This is known as Fluorescence. (See Chapter XX.) 
The luminosity of these bodies exists only through the period 
of their lumination. The color of the light emitted is dif- 
ferent, both from the impinging light and from that of the 
body itself. Reflected rays cause the colors of bodies, but the 
coloring of fluorescent bodies is due to the absorbed rays. 

Phosphorescence. — (3) A more or less continuous emis- 
sion of new light rays of different colors is produced by 
absorbed light. To this is given the name of phosphores- 
cence, of which a notable example is sulphide of calcium. 

Chemical Effects. — (4) Chemical effects may be pro- 
duced ; notably decomposition. The most intense chemical 
energy of the spectrum is found at the extreme or ultra- 
violet end. All frequencies from blue up to ultra-violet 
are also chemical in their action but less than those of the 
ultra-violet. Light exerts a chemical action in numerous 
phenomena. For example, silver chloride blackens under 
its influence; transparent phosphorus becomes opaque; vege- 
table coloring matters fade; hydrogen and chlorin gases 
when mixed combine slightly in diffused light and with ex- 
plosive violence when exposed to direct sunlight. 

Scheele found that when silver chloride was placed in 
violet the action was more energetic than in any other part ; 
but it was further observed bv Wollaston that the action ex- 


tended beyond the violet This chemical dtra- 

is hilly considered m the chi ed to 

that subject. 

Photography is based on such effii 

Mechanical <5> Light energy under certain 

conditions produces mechanical (illustrated l>\ 

* Irookes' Radiometer i. 

Electric Phenomena. — (6) By the vibrational activit] 
the oscillating light corpuscle.-, in many instances, electric 
phenomena arc caused* 

The Relation of Colors of Bodies to the Colors of the 
Spectrum. — The color of a body is n< rt identical with the c 
of the spectrum, but is dependent on the light striking it. 
Certain component parts <>\ the light are absorbed by the 
body which reflects or permits the passage of the others, 
J 11 the one instance it is opaquely colored and in the other 
transparently colored. There is, then, no color in 1>< 
the color is in the light The transparent body is trans- 
parently colorless if it permits the equal passage of all parts 
of the impinging light. For example, it is transparently 
blue it it absorbs all but the blue light Blue solution of 
copper sulphate absorbs the red and the yellow chiefly and 
permits the pa n and violet ; but not SO freely 

as blue, hence it takes on a blue color. 

Yellow color tolutions permit of the passage of the 
yellow rays, less freely the red and the green, absorbing the 
blue and the violet entirely. 

The whiteness of an Opaque body (tej)euds upon 
ability to reflect equally and strongly all the component parts 
of white light; if black it absorbs iheni. Of practical 
interest in this connection is the fact that colorless bodies 
which are equally transparent to light may vary very greatly 
in the degree to which they permit the passage of the chemi- 
cally active rays. For example, rock salt and quartz absorb 
them least of all: "Double- spat h h .da" absorbs these rays 
less than crown glass and tlinl glass. 

The red frequencies penetrate bodies much nv>n: readily 


than do the blue. A spectrum analysis of lamplight which 
has been passed through a thick sheet of paper will show 
that all blue light has been absorbed and that only the red 
and yellow remain. 

If the absorbing layer be fhicker, the red only will pass 
through. The same holds good of gases and vapors, as the 
atmosphere, for example. The matter of atmospheric 
absorption is a matter of constant reference in the pages 
which follow. 

Absorption takes place the more readily, the sharper the 
light at which the angle is reflected. 

Properties of the Spectrum. — The spectrum is regarded 
as possessing luminous thermal and chemical properties. 
As pointed out in relation to many different aspects of the 
subject, these properties are not inherent through any single 
frequency or a group of frequencies, but they exist in all of 
the different frequencies of the spectrum according to the 
substance upon which the light falls. 

The thermal effects are considered in the Physics of 
Radiant Heat as well as in the therapeutics of the subject of 
light energy, while the chemical effects especially considered 
in Chapter XVI. form an inherent part of every aspect of 
the subject of light energy in its physiologic and therapeutic 

Spectroscope. — The spectroscope is not only useful for the 
purpose of analysis of solar light but it also sustains a relation 
to the use of light in therapeutics : ( 1 ) In experimental work 
where it is desirable to exclude all but certain frequencies of 
light vibration; (2) to carefully analyze the light allowed 
to penetrate into rooms in which patients suffering from 
smallpox or the exanthemata are placed; (3) to analyze the 
spectra of the different sources of light used by the physi- 
cian ; (4) for the piu-pose of investigating substances which 
have a special importance in physiology and pathology, nor- 
mal and diseased blood, for example. The first is illustrated 
by experiments of Bernard and Morgan upon bacteria, the 
second by the prqiaraliun of the Finsen rod room, 


The Spectrum <»f each Light Source \ aries — Hie light- 
giving power in the several parts of the spectrum from 
various sooth lit is well illustrated by the follow 

classic table: 


itc light 73 

rght 74 

Lime tight 

Electric Arc light. 61 
Magnesium liglH. . 50 

Moonlight 87 

Sunlight 45 

Total light 

power express- 

eti in 



normal i 






























Ail analytical glance at this tabic will show the very great 
preponderance in sunlight from the FJ to the G line in the 
energy of the blue, which all ol the evidence thus far elicited 
has shown to he so valuable, physiologically and therapeuti- 
cally. A glance at the continuous solar spectrum will still 
further emphasize this fact. 

Magnesium Light. — The light next rich in the very val- 
uable rates of oscillating light energy is the chemically active 
magnesium light, which, as compared with the sun, is as 
I to 2*971. This is the most intensely active chemically 
of all sources i artificial light, but it hums awav with very 
great rapidity so that it is impossible to keep a continuous 
powerful illumination, as is necessary in all therapeutic work. 
Additionally it gives off a great deal nf smoke, which pre- 
cludes 1 lie possibility of using it for therapeutic purposes, 
rich as it is in the blue frequencies and powerful as it is 

It will he seen from the pages which follow upon the 
electric arc that it amply fulfils the conditions for an artifi- 
cial source of light energy. 

Influence of Atmospheric Conditions. — -Ultra-violet ab- 
BOipti nlmg to Cotnu, 1 is essentially due to the mtro- 

*La nd alter : S pect nun 


gen and oxygen of the air, although it is generally attributed 
to the presence of the varying constituents of the air, water 
vapor, carbonic acid and dust, factors which may possess a 
contributory effect. All wave lengths of less than 307/^ are 
thus absorbed. This absorption is also influenced by the 
movement and the temperature of the air. 

According to Rowland's tables of wave lengths, the water 
vapor and oxygen of the atmosphere are the only substances 
which produce absorption in the visible region, while nitro- 
gen, carbonic dioxide and ozone appear to exert no in- 
fluence. 1 

Thus, it will be seen, that the absorption varies greatly 
for the different frequencies. The violet which are the 
chemically active frequencies suffer more than the green and 
yellow, which are the most effective in the growth of plants; 
and these again more than the red ; and the red, in their turn, 
much more than the low pitched slowly vibrating waves be- 
low the red which, though invisible, are still powerful 
carriers of energy. Generally speaking, according to 
Young 2 it may be estimated that at the sea level, in fair 
weather, neither excessively moist nor dry, about 30 per cent, 
of the solar radiant energy is absorbed when the sun is at 
the zenith, and at least 75 per cent, at the horizon. 
Of the rays striking the upper surface of the atmosphere, 
between 40 and 50 per cent, therefore are generally inter- 
cepted in the air even when there are no clouds. 

According to Langley the following percentage of the 
frequencies of the different regions of the spectrum pass the 
atmosphere : 

Ultra-violet 39 per cent. 

Violet 42 " " 

Blue 48 " " 

Greenish blue 54 " " 

Yellow 63 " " 

Red 70 " " 

Magnesium light : Infra-red 76 " " 

'Landaucr : Spectrum Analysis. 
*The Sun, Young. 



The Electric Arc. 

( Her a hundred years ago, March 20, 1800. Yolta wrote 
his first letter announcing the discovery of his pile. 

Upon tin's discovery tin scientific world was as much 
agape as in these latter days it has been over the disci 
of the X ray b) Roentgen, of Becquere] rays by Becquerel, 
aiul more recently still the discover] «»f radium, with all its 
wonderful significance to pare science by Professor and 
Madame Curie. The experimental investigation of the early 
days of the voltaic pile may be classified as follows: 1 1 1 
"Those which dealt with the effect of the current on living 
tilings. \2) Th^se which produced chemical decomposi- 
tion of inorganic matter, particularly of water. 1 3 \ Tfa «€ 
which dealt with the heating power of the current, more 
particularly with the sparks produced b] making or break- 
ing a circuit/^ 

It was this last series of experiments which led to the 
discover \ of the arc. 

At the time of Volta's discovery and subsequently, one 
of the earliest experiments was to make a spark by bringing 
the two terminals of a battery together, in order to show 
that the current from the pile of Vblta was of the same 
nature as "common electricity/* so well known to the physi- 
cian of to-day as static electricity. 

Tins was accomplished by man) observers, hut Sir Hum- 
phry Daw. October, 1800, was the firsi to try the ei 
of two well-burned pieces of charcoal as the conductors, 
Charcoal had already Turn shown to be a good conductor 
Of electricity by 1 Tiestlev. 

Da\\ reported that he found that this substance pos- 
<1 the same properties as metallic hodies in producing 
the shock and spark which made a medium of communica- 
tion between the ends <»f Volta's pile. 

In a lecture before the Royal Institution in iSm. Davy 
stated that the spark passing between two well-burned pieces 

The Electric Arc, Aryton, p. 20. 


of charcoal was larger than that passing between brass 
knobs "and of a vivid whiteness;" an evident combustion 
was produced, the charcoal remained red hot for some time 
after the contact, and threw off bright corruscations. 

Thus was conceived the idea of the electric arc. But 
there was no continuity to the phenomena observed by 
Davy. It was only the discontinuous spark. The very 
nature of an arc requires continuity, and that the two poles 
should not be in contact after ignition. Later, in 1802, 
Davy reported to the Royal Institution that he had tried the 
effect of the electrical ignition of dry charcoal upon muriatic 
acid gas confined over mercury, with the result of making 
the charcoal white hot by successive contacts for nearly two 
hours. Had there been the proper relation between the 
E. M. F. and R. of both the internal and external circuits, the 
continuity of the spark obtained would have been established 
and the electric arc then and there would have become an 
accomplished fact. 

The batteries of that earlier time were so constructed 
as to have a very great internal resistance, i.e.. small plates. 
Fourcroy, Vacquelin and Thenard, in 1801, discovered that 
this resistance could be lowered by the use of larger plates, 
and it was soon found that fewer and larger pairs of plates 
gave better results in the production of sparks and heating 
effects than a greater number of pairs with small plates. 

Numerous experiments were made in 1801, on the con- 
tinent, with the spark thus obtained from the contact of the 
two terminals of the voltaic pile, in France by Fourcroy, 
Thenard and Vacquelin, and in Germany and Austria by 
Ritter, Thormsdoff. Gilbert and Pfaff. 

Gold and silver leaf, as well as thin wires, were burned, 
causing flames to arise between the two poles. In some 
instances a single spark was obtained, in others a continuous 
and rapid succession of sparks, but the experimenters failed 
to differentiate between them, the 
co very of the electric arc, both a 
is shrouded in mvsterv." 



I ; nclional electricity, with which scientists had worked 
op to that time, presents the phenomena of a succession of 
sparks always, when the mechanism is in operation, and, 
therefore, the first observer of a succession of sparks from 
a voltaic pile was in all probability unimpressed by the 

An electric arc is after all but ,i Spark, but it is a con- 
tinuous spark, maintained after first contact of the two 
terminals or electrodes, even though there be a space be* 

tvveen the electrodes, and to insure such continuity there 
must be the necessary and definite relation between ihe elee- 
tro-niotive forte and the resistance as well as the proper 
feeding arrangement of the mechanism. 

Sir Humphry Davy was the first to describe this king 
horizontal arch of flame bv reason of which the arc is 
named* although, ai stated, it will never be known to whom 
the actual discovery should be accredited. To him, how* 
ever, is due alike the conception and description, and in 
1820, after he had shown that the flame was deflected by a 
magnet, first predicted by Arago, though unknown to Davy, 
the latter gave to the phenomenon the name of the arc. 

It is not generally realized b) physicians using static 
machines that to the discharge of the spark gap from a 
frietional machine, the first conception of the arc is due, 
although not until Volta's diseovi it possible to es- 

tablish the necessary conditions. To recognize the kinship 
of all these various manifestations of energy, luminous and 
electrical, is to unify one's knowledge of these agents to the 
end of their more intelligent use in therapeutics. 

The development of the electric arc to its present prac- 
tical position has been the result of many years of study, 
investigation and experimentation, the histar) of which, all 
down through the nineteenth century, is one of great inter 
est, and the student will find an extensive bibliography upon 
the subject replete with interest and useful knowled; 

The difference of potential, in spark discharges and also 
in the discharge from a point, between the electrodes is very 


great, several hundred volts, but the current is only a frac- 
tion of a milliampere. This is not only true of the spark 
discharges but also of the convective discharge from a 
static machine with which one is so familiar. With the 
electric arc, however, when the electrodes are in a state of 
incandescence, the potential difference is very much smaller, 
while the current is enormously greater, often amounting 
to many amperes. 

When two carbons or conductors of other metals are 
brought together and slowly separated, the electric current 
does not immediately cease to flow; in other words, if the 
carbons or rods are not too widely separated, the circuit is 
not broken, but the space between them is traversed by a 
cloud of highly heated- metallic vapor which carries the cur- 
rent. And although the current passes, there is no spark 
produced in the air, as for example, with the static machine 
or a high-tension coil, because there is not sufficient differ- 
ence of potential to produce a spark in air. The electric 
current is assumed to flow from the positive pole of the 
source of E. M. F., through the circuit to the negative pole. 
In an electric arc, the direction of the current is the same 
from the positive carbon rod or electrode, across the gap 
formed by the interruption of the current, to the negative 
rod or electrode that it may reach the negative pole of the 
source. Rut when the carbons are separated about one- 
tenth of an inch, 3 mm., an arc of violet-colored light is 
formed between them, and the ends of both become brightly 
incandescent, the positive more than the negative. This 
incandescent cloud of vapor formed between them assumes 
a bow or arc-shaped form. This bow shape exists even 
when the carbons are vertical owing to the magnetic action 
of the earth's lines of force on the current. This arc may 
be a carbon arc. an iron, silver, cadmium or a copper arc, tak- 
ing its name according to the metals employed. The color 
of the arc and the character of the spectrum produced by it 
depends upon the nature of the contacts or electrodes em- 



If copper is used, the light takes on the greenish color- 
ing characteristic of copper. With iron there LS an intense 
dead bluish white light with a great deal of violet coloring 1 . 
With carbon contacts the light produced Is of a vivid daz- 
zling whiteness. This has the quality of sunlight. The light 
from a carbon are more nearly approaches the quality of 
sunlight than the light of the metallic arcs referred to, 
should, therefore, preferably be selected, when it is desired 
to utilize the activities of the electric arc for the purpos- 
a g en e r a l therapeutic administration, for example, in an 

exposure of the entire nude body to all its radiant en< 
Not only should it be a carbon arc Inn a solid uncored car- 
bon, because the softer core sometimes used to secun tin 
greatest liberation at the center volatilizes at a lower tem- 
perature, the arc is confined bo a limited area, and, there- 
fore, there is less of the blue frequencies than with the 

This does not refer to an iron core Different sub- 
stances volatilize at different rates, and the place in the spec- 
trum of any given metal depends upon the rate of vibration 
or volatilization of that metal. For example, in a wick 
as been saturated with a solution of common salt, 
then dried and exposed to the action of heat, the heat volatil- 
izes the metal sodium, tearing its particles away from tl eir 
union with chlorine. The sodium particles vibrate at their 
rate, and the dame is filled with dense yellow light 
If this light be passed through the slit of a spectroscope, two 
brilliant yellow lines will be seen in the Spectra] field, in 
exactly the same position as Fraunhofer's black lines, but 
the remainder of it will he dark. Tins is because sodium 19 
only able to vibrate in two rates, 

The blaze from a driftwood fire at the seashore gives 
a spectrum rich in yellow, because of the impregnation ol 
the wood by the salt of the ocean. Sodium of all metals 
possesses the greatest spectral sensibility, and it has been 
ascertained that i/20OO0OCX)0 of a grain of sodium is 
enough to cause the appearance of the yellow line. The 
rates at which different metals vibrate, dependent u\am the 


temperature at which they volatilize, can readily be seen 
from Plate i. Bodies at a red heat give only a short spec- 
trum, extending at most to the orange ; as the temperature 
gradually rises, yellow, green, blue and violet successively 
appear, while the intensity of the colors near the lower 
end of the spectrum increases. In Plate i, colored, the 
spectra of certain substances examined with the spectroscope 
are shown. 

If the physician will examine for himself the spectra of 
his light apparatus he will have a very vivid picture before 
him of the rates given off by the source of light he is using, 
and as to its richness in the chemical frequencies, so precious 
in therapeutics. 

Returning, however, to the electric arc, a strong current 
flows when the carbon rods are brought into contact and 
just before separation the resistance is very great. By rea- 
son of this great resistance the carbon is raised to a very 
high temperature and a portion of it is converted into car- 
bon vapor, which is a sufficiently good conductor to allow 
a steady current to flow through it. 

The temperature necessary for the volatilization of the 
carbon is not reached at the extremities of both rods, but 
only at the positive. The temperature of the negative, ex- 
cept at its extreme point is always considerably lower than 
that of the positive. The difference is due to the fact that 
the larger part of the energy is transformed into heat at or 
near the surface of the positive carbon. The average length 
of an electric arc is 3 mm., but the distance between the 
carbons which govern the length of the arc, varies 
with the kind of carbon and with the active electro-motive 

The crater formed at the end of the positive carbon is 
due to the combustion of the carbon, and the shape of this 
crater depends upon the length of the arc. In appearance 
the crater of the positive carbon suggests the crater of a 
volcano. The end of the negative carbon is conical shaped. 
This is due chiefly to combustion, but is contributed to by 



the deposition of particles of condensed carbon vapor from 
the positive pole, which help to build it up. Both terminals 

lit, but the positive more rapidly than the negv 
This description applies to the carbons of a direct -current 

These particles of boiling carton can he seen Boating 
off frottl die positive carbon by projecting the image of the 
arc on a screen or blank wall. Tart of diem tloat off into 
the surrounding media ami part in a Condensed form, as has 
been stated, are conveyed to the end of the negative carbon. 
This is a characteristic action of the current, and partakes 
of the nature of cataphoresis or the actual transfer of sub- 
stances, from the anode to the cathode. 

The crater of an electric arc has a very high temperature, 
that of boiling carbon, 3,SOO C or 6,332 F. as proved by 
Violle, the interior of which is the brightest part of all The 
intense heat thus generated can be realized when the melt- 
ing point of platinum is considered, which is 1,773 C< Of 
3,2 njF. The size of the crater varies with the size of the 
carbons and the amount of current consumed. The tern- 
perature of the negative carbon is between 2,IOO°C, or 
3,772 l*\ and 2.5oo°C. or 4*532° F. This tremendous tem- 
perature of the electric arc renders it very efficient in electric 
welding and in operating electric furnaces. Both tempera- 
ture and luminosity are chiefly due to the conversion of e!ec- 

tiergy into heat, but are partly derived from combustion 
of the carbon in air. 

The dazzling brightness of a carbon are. a miniature 
sun in fact, is such that it can only be observed through 
smoked or densely colored glass. Upon examination in 
this way, the observer notes that the arc or bow -shaped 
bluish flame which appears in the gap between the two op- 
posed carbon- much less brilliant than the ends of 
the carbons themselves. The characteristic change in the 
shape of the arc will be noticed after it has been maintained 
for a short time, i.e., the end of the positive electrode is hol- 

1 OU1 in the form of a small crater, while the negative 


or opposed carbon has a minute nipple-like projection formed 
on the end just opposite the crater in the positive carbon. 
The positive carbon is brighter than the negative, but most 
of the light, however, issues from the crater itself. As 
the power of any body to emit light increases with its 
temperature, an inspection of the arc quickly confirms the 
statement made that the crater is the hottest part of the 

With the current strength ordinarily employed, the in- 
. candescence of the carbons extends to but a comparatively 
short distance from the tips. This is the region in which 
the burning of the carbons or the oxidation is most marked. 
After the arc has been maintained for awhile under the 
double influence of volatilization and oxidation, the ends of 
the electrodes assume a more or less irregular shape. This 
is shown in Fig. I. 

Careful observation, through the medium of smoked 
glass, of the conical-shaped ends of the carbons, will re- 
veal minute globules of molten matter, scattered here and 
there over their surfaces. These are supposed to be molten 
drops of various mineral impurities in the carbon. The 
more nearly pure the carbon the fewer they will be. If an 
iron cored carbon, positive, is used, there will be observed 
tiny drops of molten iron on the tip of the negative. 

In operating an arc, the crater does not maintain its posi- 
tion, but shifts from point to point on the surface of the posi- 
tive carbon or electrode. This is explained by the following 
fact. As the carbon is consumed by volatilization and oxi- 
dation, the edge of the crater becomes unequally worn at dif- 
ferent parts, and the tendency is for the arc to establish 
itself at the point where there is least space between the two 
carbons. In this way a new crater is temporarily formed. 
Impurities in the carbons also determine a different rate of 
volatilization with the result of the formation of the crater 
at the point where volatilization is most active. It is very- 
essential for the best results, whether as an illuminant only 
or whether it is to be employed therapeutically as a minia- 


l.loItT ENERGY. 

ture sun batli, that carbons of the greatest purity should be 

By reason of the shifting of the position of the crater 
from the above causes, the light becomes unsteady and 
flickering, which results in an unequal distribution OVCff the 
surrounding space. This has been obviated in the practical 
operation of the arc by utilizing carbons oi the smallest 
diameter Compatible with the amount of current i 
ill order lo reduce the ;m i over which ihe arc can shift, and 
also by the introduction into the centre of the carbon a core 
tter carbon. By the use <»F such a core, there is secured 
the greatest liberation from the central portion! and the con- 
sequent formation of the are at these parts. These are 
known commercially as cored carbon- I suallv but one car- 
bon is OOTed, viz,, the positive, as this is the seat of the crater, 
where the trouble arises with file ordinary carbons. In 
therapeutic work cores of iron, an iron rod passed through 
the centre of the carbon axially, or iron incorporated into W 
appropriate solidified mass are used. As iron when volatil- 
ised is extremely rich in chemical activities, its use is very 
desirable where the production of the maximum of ultra- 
violet rays is desired* 

By reason of the rapid vaporization of the positive carbon 
it wastes twice as fast as the negative. Tins is the re 
why it is necessary where large currents are used that the 
positive carbon should have twice the thickness of the nega- 
tive carbon. 

The arc proper is separated from the crater by a thin 
layer of carbon vapor, which has in .til probability a high 
specific resistance. This laser of carbon vapor is of bulbous 
shape, violet in color and consists of conducting carbon 
particles condensed from the vapor. 

The region around the are in which the combustion is 

lg on is distinguished by a green flame. Eighty-five 
per cent, of the light of the arc comes from tin positive ear 
bon, 10 per cent, from the negative, and 5 per cent. From the 
arc proper. Although the temperature of the are is high, its 


emissive power is feeble. The sources of light in the arc are 
( 1 ) the crater, (2) the remainder of the hot end of the posi- 
tive carbon, (3) the white hot spot on the negative carbon, 
(4) the remainder of the hot end of the negative carbon, (5) 
the arc vapor. 1 

The light emitted by these 5 sources together is called 
by Mrs. Aryton the light of the arc ; while the light emitted 
by the arc proper she terms the vapor light, or the light of 
the vapor. 

It is this vapor light which concerns the physician. As 
has been shown the color is that of violet, and from it pro- 
ceed the short high frequency wave lengths or ultra-violet 
rays as well as the blue and violet, all of which have well- 
marked actinic properties. The longer the arc the more of 
the vapor mist. This means that the arc mist would be 
cooler as the average temperature of it is lowered by in- 
creasing the length of the arc. As the carbons are drawn 
apart, the arc stream tends to spread out further. The 
amount of light emitted by the unit area of the crater is 
practically the same when the power supplied to the arc is 
raised sixty-fold, and is independent of the size of the car- 
bons and of the length of the arc. This was demonstrated 
by Violle. 2 

By increasing the current, with given carbons, at a given 
distance apart, the size of the crater is increased, and there- 
fore the total amount of light emitted, but there is no increase 
of the amount per unit of area. If the temperature of the 
crater is that of the volatilization of carbon, it could not be 
increased, provided the pressure remained constant, however 
greatly the power applied was increased, and therefore it 
would not be exacted that there would be more light emitted 
per unit of area. The principle involved is the as in 
boiling water. The temperature of boiling water cannot be 
raised even by using a more powerful source of heat. The 

1 Aryton. p. 314. 
2 Ganot's Physics, p. 869. 

9 2 


temperature of the space between the carbons may be much 
higher than that of the surface in the same way that steam 
can be superheated above the point at which it is evaporated, 
there being in fact, no limit to the possible rise in ten,; 
tore. Since the current is conducted by that highly he 
vapor present! it is to be expected that such a conductor \\\U 
be heated by the passage of a current the same as a solid 
or a liquid. 

An electro-motive force of more than 40 volts, usually 
from 40 to 50. is necessary to maintain a steady arc between 
carbon points, giving a current of 10 to 15 amperes. It is 
generally assumed that this high E. M. F. is needed rxv 
of a back E. M. F. of 39 volts at the crater in the positive 
carbon. A large amount of energy is needed there for the 
vaporization of the carbon. This high apparent resistance 
of the arc, obtained by dividing the difference of potential 
by the current, is due to this back E. M. F. This counter 
E. M. P., which is variable with the current and other con- 
ditions, is generally attributed to a combination of two Of 
more M'parate electro-motive forces, one due to the volatili- 
zation of the carbon, another due to the thermo-electric 
1 fifed at the positive carbon, and perhaps still another ther- 
mo-electric potential at the negative carbon. 

According to J. J. Thomson this potential difference is 
determined by the rate at which the negative electrons are 
given off. An arc of 3 mm. or l/io of an inch, has a resist- 
ance something less than an ohm. For a 10-ampere arc 
from 1/16 to i ''8 of an inch in length, the resistance is given 
at from 1/10 to 1/2 an ohm, while roughly speaking a Pi 
ance of 5 ohms for an arc one inch in length is given. The 
true length of an arc is from the lwttom of the crater to the 
tip of the negative, not from the edge of the crater which 
is only its apparent length. This resistance of an arc, like 
that of any other conductor, increases with its actual length, 
and diminishes with its cross section, It has been suggested 
by Mrs. Arytoii that the film of carbon vapor close to the 
crater has a relatively high specific resistance and tint the 


temperature of the crater may be accounted for by its resist- 
ance rather than assuming a large back E. M. F. 

Care should be taken in the adjustment of carbons. If 
they are too far apart, or too close together, the arc is noisy 
and fluctuating, and if the distance between them is too 
great the arc flares and flickers from side to side. Thus the 
chemical combustion is increased, with the result that the 
electric efficiency is reduced wben the distance is too small, 
while the illuminating power of the arc is reduced by each 
carbon acting as a screen for the other, and the crater is 
diminished in size. By the reduction in size of the latter, the 
efficiency of the arc in therapeutic work is diminished, for 
the longer the arc and the larger the crater, the greater num- 
ber of the short high frequency waves or ultra-violet light, 
intrinsically so valuable. This is because of the increase in 
chemical combustion. The longer arc offers a greater oppor- 
tunity for the air to oxidize the carbon. The longer the arc 
the greater the E. M. F. required, and when more than 80 
volts is used there is a great increase in the quantity of 
violet light given off. This is not well for purposes of illu- 
mination, but it is just what is needed for therapeutic work. 

There is no difference in the appearance and consump- 
tion of carbons when an alternating E. M. F. is used, for 
by reason of its physical nature changing at both signs, posi- 
tive and negative, with each alternation, there is no polar 
action as with the direct current. Each carbon maintains a 
rounded appearance, there is no formation of a crater and 
they are consumed at the same rate. The upper carbon 
wastes 8 or 10 per cent, faster than the negative, due to the 
ascending heat. When an arc is fed by an alternating cur- 
rent the arc is no longer a continuous flame, but is lighted 
and extinguished at every reversal of the current. 

The candle-power of an electric arc depends upon its 
volt-amperes. For example, an arc with a pressure of 50 
volts, and giving a current of 15 amperes, expends a power 
of 50 volts X 15 amperes, or 750 volts. This is equivalent to 
about 1 horsepower. As .75 of a volt is required to produce 


Lit, HI I 

the light of one candle, 750 volts will gfr candles. 

Therefore if one L ^"^ r two arc lamps connected in 

series, with a pressure ol JO volts antl a current of 15 
amperes, in an electric arc hath, in which the patient lies 
mirlc, tin- bod) is bathed in a sea of light of 
power, an<l while to each square inch of surface but a small 
amount of light energies arc delivered, there is a very con- 
siderable total of energy expended by reason <>f the verv 
targe square inch are L i.e., the entire body. This 

effect is increased by reason of the cabinet enclosure and the 
white enamelled walls, providing as they do the best 
reflecting surfao 

In the Light Institute at Copenhagen, under the direction 
of Ftnsen, lamps of 20,000 c >wer are used, This 

means a tremendous volume of light, and with the inctt 
current, 80 amperes and upwards, and the increased diame- 
ter of the carbons or electrodes, there is afforded a larger 
crater, which means a larger unit of area. And as it is the 
light emitted by the are proper, called the vapor light or the 
light of the vapor, 1 which is so rich in chemical activiti 
short and high frequency waves, fa m the blue to the ultra* 

Violet, the advantage of lamps of high candle-power can 
readily he seen. This quantity of light, 50 active, chemically, 
isential in the treatment of well-organized and deep- 
seated skin conditions, as in long-standing cases of lupus 
vulgaris for example. 

Quantity Necessary as with the Ton tin nous Current. — 
The good results obtained from the selected chemical 
activities of the electric arc from lamps of high amperage 
and enormous candle-power, in the treatment of deep-seated 
and long-standing lesions, is comparable to the use of the 
continuous current, in I ml Si m ling and deep-seated path- 
ologies as for example, exudates about the sheath* 
tendons and the articular surface of joints. 

From the use of currents of high potential and high 1 r» 

'Aryton, [>. 314. 


quency it is not possible to obtain results as quickly in these 
cases as with the chemical action of the continuous current. 
There is a chemical action with both, but there is not that 
quantity, coulombs per second, with the one that there is with 
the other, which is essential to the production of the changes 
necessary to the absorption of the organized exudate. This 
is likewise true of condenser lamps, excited by high-tension 
coils or static machines, and also iron electrode lamps of low 
amperage. The chemical activities thus produced have not 
the quantity of the larger lamps, which is absolutely essen- 
tial in the most thoroughly organized skin pathologies or 
wherever a deep-seated action is required. For more recent 
and superficial conditions the lamps of lesser quantity are 
equally good. 

But lamps of lesser amperage do good work if the light 
emitted by the arc proper or vapor light is utilized near 
its source. By their passage through air, the precious ultra- 
violet waves are absorbed to a greater or less degree, accord- 
ing to the distance. The same is true of that portion of the 
ultra-violet region known as the bactericidal region when 
passed through water. Tt is estimated that four-fifths of 
the bactericidal activity is lost in passing through but 
2.5 cm. of water. And as in the Finsen apparatus the con- 
densing lens is at least three feet from the vapor light 
emitted by the arc proper, and passes through from 4 to 
6 inches of water, there is a very considerable loss. With 
the enormous candle-power of the lumps used by Finsen, 
this is of little moment, but with the lamps of lesser amper- 
age commonly used in office work, it becomes a matter of 
very great moment. In using lamps of lesser amperage, 
without water-cooling cylinders and near the arc itself, the 
difference is not proportional to the diminished candle- 
power, as in the latter instance few of these short high-fre- 
quency waves are lost as compared with the higher candle- 
power lamps where the beam is not only used farther from 
its source, but filtered through water. All the energy of 
the light from the arc, whe ' : ^ the form of light, heat 



or anything else (gases produced), radiates from the middle 
of the crater. 

asurements which have been mad< >nd- 

enee with the compound radiant energy uf the sun's sur- 
face, viz., at the rate of 100,000 horsepower to the square 

There Is always a definite ratio between the em 
any body ami its te mpe r a ture, therefore, if the radiant of 
two bodies 13 the Same, so is their temperature. That of 
the radiant dot of the electric arc is nearly 6,500 l\ This 
would indicate that the temperature of the sun* surfai 
the same, in view of the fact of the correspondence in meas- 
ure of energy. 3 

It has been shown that an increase of pressure does not 
increase the temperature of volatilization. An increase in 
the current strength or the quantity of electricity which 
passes per second through the are has no increase upon the 
temperature of the arc, and only tends to increase the amount 
of carbon volatilized, and, therefore, the area of the crater. 
This affords, as has been pointed out, an increase in the 
unit of area. 

The temperature of boiling carbon is 3,500 (\, and is 
the highest which has yet been produced artificially, [f 
conditions existed under which a temperature in excess of 
boiling carbon could be reached, it would mean a soun. 
light richer in the visible and invisible frequency of light, 
or short and high frequency vibrational activity; a light not 
only of higher intrinsic energy, but of greater total energy, 
capable of profi Hinder chemical action, the therapy of which 
19 yet unknown. But iron which volatilizes at a temperature 
of [,6oo°C, although volatilizing at a lower temperature, 
has a high rate of vibrational activity, and gives a spectrum 
rich in the ultra-violet frequencies, but it does not vib 
at the slower rate (hat gives the visible chemical rates and 
those below, and the light, therefore, while p ig the 

'Professor Dolbcar, Press clipping. 


high intrinsic energy does not possess the total or complex 
of energy essential to the best therapeutic work. In the 
much lower temperature at which volatilization takes place 
is to be found the reason why, when an iron-cored carbon is 
used for the positive electrode in the formation of an arc, 
the production of heat is so much less than with pure carbon, 
which volatilizes at a temperature of 3,500° C. or 6,332° F. 
And this lower temperature in connection with its extreme 
richness in ultra-violet rays, i.e., inherent rate of vibration, 
renders carbons with iron cores very desirable for the thera- 
peutist. Iron is used alone in some arc-light mechanisms 
for therapeutic purposes. Clinically, however, the better 
results are obtained with the lamps of larger amperage where 
carbons or carbons cored with iron are used, than with lamps 
of small amperage with iron electrodes. As the most intense 
chemical combustion is the seat of the highest chemical 
activities, there is every reason to believe that the higher 
temperature at which the volatilization of the carbon alone 
or that of carbon combined with iron, is the one at which the 
greatest quantity of ultra-violet rays are given off, and, 
therefore, is the better source for therapeutic work. 

Bodies become luminous at a temperature of 500° C. or 
932 °F., but the increase of luminous intensity increases 
with the temperature. This will not be true of the cold light 
of the future, which will be a light devoid of temperature 
and containing the maximum of visual rays. The efficiency 
of the light of the firefly is practically 100 per cent. ; in other 
words, the firefly does not seem to emit any frequency of 
light vibrations, which are not within the limits of visibility ; 
while all practical mechanisms for the production of artificial 
light for illuminating purposes requires that the tempera- 
ture of the luminous body be raised to such a point that the 
frequency of oscillation of its molecules is such as to cause 
the emission of light as well as heat. This means much 
more dark heat than luminous heat, and the work of Tesla, 
of McFarland Moore, of Cooper Hewitt, in the direction of 
producing luminous actr :f hout will unques- 

9 8 


tionably result in a cold light, as the illuminating pOWi 
the fiitim- 

Professor Langiey' states thai the Cuban firefly spends 
the whnlr of its energy upon the visual rays without wasting 
any upon heat, and is some 400 Inn efficient as a light 

producer than the electric arc, ami even 10 times more efri- 
cient than the sun in this resp 

The luminous efficiency of the arc lamp is practically as 
thai of anj known artificial source, being about 

] i **3 l^ r Ottlt, while it 14 nenrh 3 times greater than 
that of the normal incandescent filament, and al>out 6 times 
greater than that of oil Of gas flames. 2 

In a consideration of the electric arc for therapeutic pur- 
puses the phenomena which take place in the arc mist dur- 
ing the activity of the arc are not only of interest but im- 
portance. Since Sir William Abney 5 first announced that 
the temperature of the crater was that of volatilization of 
carbon, it has never hem doubted but that the stuff of which 
the arc was composed consisted chiefly of the vapor thus 
volatilized. Ft leaves the positive carbon without doubt a? 
vapor, but its temperature must be lowered by the cooling 
action of the air. It must therefore, he considered at a 
very shorl distance from the crater, * )f this there can be 
but little doubt, and in her work on the electric arc, Mrs, 
Ai yton expresses it as her belief that the vapor, in leaving 
the crater, acts just as steam does when issuing from the 
mouth of a kettle. Through a short distance, small enough 
for its temperature to continue unaltered, it still remains 
I ; at a greater distance it is condensed into carbon, 
fog or mist. The true vapor is probably invisible, just 
as water-vapor is (die spare that is always between the 
arc and the crater confirms this view ) but the mist is visible 
The resistance of true vapor is very great, and consequently 
the resistance of the thin layer of the vapor that lies over 

'Electrical \Wrl<l and Engineer, X N 

a Hoii-t'iT] ami Ki-nnelly, ElectftC Arc Lighting. 

"Aiyton, p 


the crater is so great as compared with that of the remainder 
of the arc, that it is usually supposed not to be a resistance 
at all but a back E. M. F. According to Stark, 1 there is 
a back or counter-electromotive force of the arc when the 
anode is very hot, and it represents the sum of the internal 
electromotive force of the anode and cathode, but is much 
smaller than the minimum tension. The latter is not 
due to the counter E. M. F., but to the fact that a mini- 
mum of work must be done at the cathode in order to 
produce the radiation of negative electrons in sufficient 

By the passage of the current through this great resist- 
ance, the heat evolved (the greater the resistance, the great- 
er the production of heat) is sufficient to volatilize the sur- 
face of a part of the positive carbon, and thus to keep up 
the supply of vapor. 

The part of the surface thus volatilized becomes hollow 
with a short arc, and the crater is formed by the action of 
the heat supplied to it by the thin layer of vapor over its 
surface. According to this theory of the arc, the tempera- 
ture of any horizontal section of the mist must depend upon 
(i) the temperature at which it left the crater, (2) the con- 
stant supply of heat conveyed to it, by radiation from the 
crater, (3) the heat evolved by the passage of the current 
through it, and (4) the cooling effect of the surrounding 

The average temperature of the mist must be lowered 
by lengthening the arc, and consequently its average density 
must be increased. 2 

The following facts indicate that the arc mist absorbs 
an appreciable amount of The light emitted by the crater: 

(1) That this mist shares with candle and gas flames the 
power to hide anything placed behind it, as if it were 
opaque, not due to too much light, but absence of light. 

(2) The acknowledged and proved existence of solid par- 

Dec, 4, 1904, 



tides in it. (3) Its casting a shadow which can hardly be 
due merely to refraction. 1 

All oi these Eacts concerning the mist arc of both interest 
and importance in connection with tlie use of the chemical 
activities of light in therapeutics, as the evidence points tO 
the vapor <>r mist as their source. 

The spectrum of the arc is not only rich 111 the luminous 
and thermal activities, but is especially rich in the chemical 
activities. And by the chemical activities is meant not util\ 
those of the ultra-violet region, so much talked of, rich as 
that region is in intrinsic energy, but the violet and blue 
violet as weiL 

The Spectra of the Electric Are, — The spectra which are 
formed by artificial lights rarely contain all the colors of the 
sr .lar spectrum; but these Colors are always found in the 
solar spectrum and in the same order. Their relative Inten- 
sity is also modified. The shade of color which predominates 
in the flame predominates in the spectra of that flame. In 
yellow, red and green flame, red. yellow and green predomi- 
nate in the spectra. It was shown by Sir \\\ Abney.- as will 
en by tables <>( light values given below, that the crater 
light of the electric arc was verv like sunlight, but that it had 
an excess of orange and green rays and a slight deficiency of 
blue. Taking the intensity of ml as the unit, the composi- 
tion of direct sunlight, of the carbon arc. and of gaslight, 
were found by Abney respectively, as follows: 


Rtd 100 

Green 193 

Vi.ilet 228 

Carbon Arc 

Red. 100 

Green 203 

Violet 250 


Red log 

Green. . - 
Violet, . . 

The hardness of the carbon, the material of the core, 
the current and the voltage, all influence the composition 
of the electric arc. By hardnesi the maximum temperature 

'Arytnn: The Electric Arc. 

*Rqxjrt on the Action of Light on Water Color*, C. 5455, iS 
pj>. 25 and opt 


of the crater is determined, while the current and voltage 
alter the properties of the light fluxes coming from the yel- 
low crater and from the violet arc stream. The vapor of 
the core acts to color the light as well as to determine the 
volatilization point of the crater. 

Abney's spectroscopic examinations were made so as 
to interpose as little of the arc as possible between the 
spectroscope and the crater, and in this way he secured the 
rays from the crater only. This crater light when seen 
through a small quantity of mist is yellower than sunlight, 
but when it has penetrated through a very long arc, the 
.color is a bright purple. This is very commonly shown in 
the purple coloring of the opalescent globes surrounding 
the arc lamps of the street. This purple coloring is evi- 
dence of great chemical activity. It differs only in degree, not 
kind, from the violet coloring of X ray tubes and the tubes 
of glass containing radium. The light of the crater becomes 
tinged with violet or purple as it passes through the arc, 
and the tint deepens as the arc is lengthened. In this, then, 
must be found the reason for the establishment of a long arc 
when the maximum of ultra-violet rays is required. For 
next the violet come the higher frequencies of the ultra- 
violet region. 

If a light becomes colored by passing through screens 
of colored glass, blue, red or green, for example, the ex- 
planation is to be found in the fact that the glass interposed, 
whatever its color, absorbs certain colors and permits 
other rays to pass. For example, with blue glass, the rays 
giving other colors are absorbed, therefore a blue glass 
screen gives the maximum of chemical activities below the 
ultra-violet region, but not the ultra-violet, however, as 
glass is not transparent to ultra-violet frequencies, i.e., below 
30 micro-centimetres. 

The following is a very rational explanation of the phe- 
nomena which occur in the electric arc to produce the intense 
violet mist. The arc, except a thin layer quite close to the 
crater, consists of a mist of solid carbon particles, which are 



continually forming and falling, surrounded by burning 
gases. The vapor ami gases must absorb a minute, p 
bly an inappreciable portion of the light that issues from 
the crater, If this were all, tliere would probably be no 
maximum of light with a given length of arc, but the solid 
carbon particles have to be reckoned with. The whole 
quantity of light absorbed might still be too small to notice, 
if the light simply passed through each of these particles it 
encountered and suffered only the small amount of absorp- 
tion i that would naturally occur. 

But a ray of light when it encounters a red hot particle 
is not only refracted, but some of it is reflected, so that each 
ray may be reflected from particle to particle, and traverse 
the mist hundreds of times before it finally emerges. At 
each reflection and refraction part of the light that the car- 
bon particle is capable of absorbing is absorbed, and accord- 
ing to physical laws, a ray that has suffered much internal 
reflection must emerge in a different state froni that in 
which it left the crater. 

If the carbon particles were capable Of absorbing the 
orange light and a certain amount of die green, permitting at 
the same time the passap 1.1 the violet light, then each suc- 
cessive reflection or refraction would result in more violet, 
while that which had encountered many particles would be 
entirely violet, A dazzlingly brilliant light is not given by 
incandescent gases alone, and in looking at the arc mist 
only, screening off the whole direct light from both carbons, 
the part of the craler light transmitted to the eye from the 
solid particles, entirely swamps the feeble light emitted by 
the gases, and a brilliant violet or purple light is perceived 
In this way is the brilliant light of the arc alone accounted 

A simple experiment shows that the light emitted by 
the arc mist is violet, vvhile that emitted by the crater and the 
white hot spot on the negative carbon is white. Take a thin 
metal plate containing a horizontal slit, 1 about 1/16 inch in 

Wryton, pp. 35& 359* and 360. 


width, hold it vertically near the arc, so that the slit is about 
equidistant from the ends of the two carbons. Have a verti- 
cal white screen a foot or two away upon which to receive 
the light from the arc that passes through the slit. This 
light will form three horizontal bands on the screen, the 
upper and lower ones white, and the middle one of a bright 
violet. The slit corresponds to a pinhole elongated horizon- 
tally, therefore the upper white light proceeds from the 
negative carbon, the lower from the crater, and the middle 
violet band is lighted from the mist. 

Or again, the upper carbon and part of the arc may be 
shaded with any opaque body, one's hand, for example. The 
shadow on the screen is edged with a broad band of reddish 
violet and represents the portion of the screen that is illumi- 
nated by the mist and the negative carbon alone, the red-hot 
part of the carbon gives the rosy tinge. Below the band is 
the part illuminated by all three sources, — crater, mist and 
white hot spot, and this naturally looks quite white when 
compared with the violet spot. 

It is concluded by Mrs. Aryton, whose experiments 
are quoted, that the crater light is far yellower when 
emitted than when measured, and as the use of it thera- 
peutically corresponds more nearly to the position of the 
photometer when it is measured, it follows that the high- 
est chemical activities are easily available for such pur- 

When an arc is lengthened, the arc mist is cooler on the 
whole and under these circumstances there would be more 
solid particles, and each ray stands a better chance therefore 
of encountering one or more of these particles before emerg- 
ing. Thus, more of the light on the whole would be ab- 
sorbed, and more of the rays robbed of all the light the 
particles were capable of absorbing before emerging, so that 
on the whole, the light would be more violet than with a 
shorter arc, as it actually is. Every arc-light mechanism 
used for therapeutic purposes should therefore be adjusted, 
for as long an arc as its automatic feed arrangement will 


lu;iit energy. 

permit, in order to secure the maximum violet and ultra- 
violet ra\ v 

In drawing a long arc, there is ample room for lateral 
ding, therefore its resistance is capable of being 
markedly diminished by an increase of current strength. 
By spreading laterally in all directions, the cross-sectional 
area is increased, and an increase in resistance by reason of 
the length of the arc may he tnott than compensated by the 
decrease in its resistance attendant BpOD the increase in the 
area of the cross-section. This diminished resistance m a 
long arc, from which the highest chemical activities are se- 
en ret 1, means diminished heat 

Such an arrangement is impractical when the arc ts used 
Eof illuminating purposes, as "almost the whole of the in- 
creased power thai has to be supplied to the arc when it is 
lengthened, is swallowed up by the mist, ami is practically 
■d. And the ideal condition where illumination only is 
desired would be to have the carbons nearly touching were it 
not thai the negative carli pa some of the light." 

Professor and Mrs. Arytnm as a result of a series of ex- 
periments, combined with careful observation and exact 
photographic records, found that when a direct current silent 
arc is maintained between vertical carbon rods, the positive 
carbon being uppermost, — 

T. The tip of the positive carbon is white hot, and the 
tip of the negative has a white hoi spot on it. 

II. A white hot crater forms in the end of the positive 
carbon, and a more or less blunt point forms on the end of 
the negative. 

III. The space between the tWO is filled by a violet 
light, the shape of which is defined by a shadow, which in its 
turn is bounded at its sides by a green light. 

IV. The en Is of both carbons are tapered, and the 
length of the tapering parts is increased both by increasing 
the current and by shortening the arc. 

V. The diameter of the crater increases as the current 
increases, and also as the length of the arc increases. 


VI. With uncorcd carbons, the violet part of the arc 
is bluer, and all parts of the arc are larger than with cored 

VII. With uncored carbons, the violet part of the arc 
is of the form of an oblate spheroid when the arc is short. 
gourd shaped when it is long and the current is very small. 

VIII. With cored carbons, the violet part is of the form 
of an oblate spheroid when the arc is short, gourd >haped 
when it is long, and sometimes almost of the shape of a 
figure 8 when the arc is very long for the current flowing. 

IX. When the negative carlxm is cored, a crater is 
formed in the tip exactly as if it were a positive carbon. 1 

Hissing Arcs. — It will be noted in operating electric arc 
mechanisms, that at times the arc gives out a hissing sound. 
This has been the subject of elaborate study, investigation 
and experiment by Mrs. Aryton. who has shown that the real. 
crucial distinction between a silent and a hissing arc is pro- 
duced by the crater Incoming too large to occupy the end 
only of the positive carbon, and by its, therefore, extending 
up its side. When the crater occupies the end only of the 
positive carlx)ii. the arc is silent : but when it not only occu- 
pies the end but extends up the side as well, the arc hisses. 

The extension of the crater then is the cause, and this 
extension is due to the presence of air. When an arc is first 
formed there is always a hissing sound which is due to the 
presence of air around the carbons when they are cold, so 
that when the crater is first made its surface must combine 
with the air; just so when it hisses it is due to an inrush of 
air into the arc. Hissing is avoided by the use of enclosed 
arcs, preventing thereby access of air to the arc, but in 
therapeutic work enclosed arcs should never be used because 
of the intervention of the glass enclosure. 

A hissing arc is accompanied by a sudden diminution of 
potential difference. This diminution is due to the oxygen 
in the air getting directly at the crater and combining with 

x The Electric Arc. Mr*. Aryton. 




i lie carljon at its surface. No such effect is produc&d by 
nitrogen, carbon dioxide or hydrogen, hut the same is true of 
air showing that this diminution of potential difference in a 
hissing arc is due to the presence of oxygen. With the hum* 
ming and hissing a green light appears in the crater and 
with hissing, clouds partially cover the crater; and the car- 
bon vapor heo nues llattened run between the carbons. 

The student who is interested ifi the phenomena of the 
electric arc will find Mrs. Anton's study of it most inter 

Alternating-Current Arcs, — Alternating-current arcs 
may he used for all therapeutic work other than with con- 
densing or focal lenses as in the 1' in sen tube, 

:ception is \\m to the fact that in an alternating 
current the direction of the flow is constantly changing and 
each carbon becomes alternately positive and negative. 

In an alternating-current arc there is no crater formed 
at the end of the positive carbon, nor opposing nipple-like 
projection on the end of the negative. There is therefore a 
different distribution of light and the rate of the consump- 
tion of the carbons is approximately equal. 

Alternating-current arcs are considerably influenced by 
the frequency of the alternations. If the frequency is below 
35 periods or double reversals per second, the arc distinctly 
dickers. This produces an unpleasant varying visual effect 
owing to the rapid extinction and production at each pulsa- 

tion of the current. A frequency of about 60 cycles or 120 

reversals per second is generally regarded as the most 

If the frequency is above 70 cycles or double reversals 
per second, alternating arcs develop a tendency to a distinct 
humming note which at higher frequencies becomes annoy- 
ing. But 35 to 4<> volts pressure are required by alternating- 
current arcs. An alternating pressure of 35 volts means a 
maximum pressure of about ?o volts in each wave, or if an 
E. M. F., which rises to 50 volts at the peak of each wave be 
used, the effective E, M. F, will be about $5 wits, 1 be real 


pressure required is therefore practically the same for both 
continuous and alternating-current arcs. There may be 
a wide variation in amperage as with the continuous current 
but for an ordinary electric arc cabinet 15 ampere arcs 
are sufficient. In common with continuous-current arcs 
alternating-current arcs require a regulating lamp mechan- 
ism in order to maintain the carbons at a constant distance 
apart. The character of this mechanism is changed to meet 
the changed conditions, that is, an almost equal burning of 
the two carbons. Alternating-current arcs however can 
never be connected directly with the mains of the generator 
supplying alternating currents, as they can to the mains of 
the generators supplying continuous currents. An appara- 
tus known as an alternating-current transformer must 
always intervene between the mains of the generator and 
the lamp mechanism. These transformers are provided with 
both primary and secondary circuits ; the primary is con- 
nected directly with the generator at a comparatively high 
pressure 1,000 to 2.000 volts being very commonly used. 
The secondary circuit is connected with the arc-lamp mech- 
anism or incandescent for that matter wherever installed, 
usually at a pressure of about 100 volts. 

In the event of a single arc lamp being used the pressure 
is about 33 volts. If however a number of incandescent 
lamps have to be supplied, a pressure of 100 volts must be 
generated by the secondary coil of the transformer, but in 
order to keep this pressure down either a resistance or a 
choking coil must be introduced to cut the pressure down to 
30 volts. 1 

The Influence of a Magnetic Field upon an Alternating- 
Current Arc. — The alternating-current arc has been shown 
recentlv to have characteristics peculiarly its own. C. H. He- 
dell 2 points out additionally its very interesting behavior when 
in a magnetic field. That any arc may be "blown out" by the 
approach of the poles of a magnet is a well-known fact. If 

* Houston and Kcnnelly: Electric Arc Lighting. 

f C. H. Bedell. Electric World and Engineer, Sept. 13, 1902. 

i o8 

Lir.Hi i 

a magnet of the horseshoe type be used, "blown out' 
reedy describes the phenomenon. If a har magnet is used, 
the arc is forced out at right angles to the line of the mag- 
net and not directly away from it, as the "Wowing Ottt" 1 

would lead one to suppose. The principle 19 the same as 
that which governs the actkwi Oil wires carrying current on 
the surface of a motor armature, i.e., the direction of the 
flow of the current, that of the lines of magnetic force, ami 
direction of movement are all at right angles to each Other. 
If the north pole of a liar maguci be presented to a direct- 
current arc and the current Bows down, the thrust will be 
to the right; if up, the thrust will be to the left. With an 
alternating-current arc, however, the two effects are com- 
bined, and the arc appears to have two wings. While these 
wings appear continuous, they do not i \ist at the same time, 
luu follow the alternations of the current 

The appearance of the arc under the influence of the 
magnetic field is interesting, as the wings may easily he 
made bo have an extent of 5 inches from tip to tip, and 
with an upward curve due to the currents of heated air. 
In attempting to photograph such an arc. it was found n< 
sary to shield the lens from the strong violet rays of the 
arc proper, in order that sufficient exposure might be 6b? 

Uuned on the wings. The ends of the carbons, as shown h\ 
the photograph, although brilliantly ineandes* not 

appear to give out many chemical rays. A short exposure 
was made to suit the violet arc, and the result indicated that 
but little violet light was given out by the incandescent ends. 
The question, therefore, arises, is not the curve of illumina- 
tion for actinic rays for any arc lamp quite different (mm 
the curve of illumination for visual rays? Graphic ilhistra- 
of the current curve, l»*»ili before and after separation 
by magnet, are shown in Bedell's article. 

Carbons and Methods of Arrangement. — As has been 
indicated in previous pag« B there are two classes of carbons 
Used in arc lighting, viz., solid and cored. Their diameter 
varies according to the voltage ami the current consumed. 


For those in general use, the average resistance is 0.15 ohm 
per foot. 

Solid Carbons. — These vary according to their purity, 
molecular structure and hardness. The best are known as 
the electra or Nuremberg carbons, and are manufactured 
in Germany. 1 The electra of domestic manufacture are not 
comparable to the Nuremberg carbons as to purity and hard- 
ness. The former resemble graphite in these respects. Car- 
bons are very apt to be filled with impurities, all of which pre- 
vent the securing a true carbon spectrum. There may be an 
increase of the frequencies of one or another portion of the 
spectrum, by reason of such impurities. If impregnated 
with iron pyrites, for example, there will be an increase in 
the ultra-violet frequencies, which is not objectionable for 
considerable therapeutic work. Where iron is used, how- 
ever, it is better it should be pure. Sodium, on the other 
hand, would give an increase in yellow. 

Cored Carbons. — These are solid save for a hole which 
runs axially through the length of the carbon. This hole 
is filled with some material softer and more readily volatil- 
ized than the remaining carbon. Usually, it is a mixture 
of carbon and some metallic salt. The object of this core in 
illumination is twofold : ( 1 ) to decrease the voltage for a 
given length of an arc, or ( 2 ) to increase the length of an 
arc for a given voltage. Initially, this has the effect of re- 
ducing any irregularity in carbons or the feeding mechanism 
to a less percentage of the whole length. In addition, the 
core, by affording a plentiful supply of vapor, tends to 
maintain a stable condition of the arc. By the use of a 
cored carbon, the tendency is for the arc to remain located 
in one spot, i.e., at the core, instead of travelling in an irregu- 
lar fashion all over and around the end of the carbon in an 
effort to establish the way of least resistance. The core 
does that, and thereby maintains a steady non-fluctuating 
arc. The core of a carbon may also be used for the pur- 

imported by Hugo Reisinger, 71 Broadway, New York City. 



pose of intensifying certain portions ol the spectrum. This 
is very important in therapeutics where it is desired to in- 
crease the number of the highest chemical frequence* 
ultra-violet rates of vibration. For this purpose carbons 

OOred Willi iron aft Of great service. The ones manu- 
factured in this country are inferior to those imported, 
The Nuremberg carbons are prepared with powdered iron 
incorporated into the mass which forma the core, When 
similar carbons are placed vertically one over the other, 
their relative consumption depends upon the amount carried 
off by: (i) volatilization and electrolytic action; (2) oxida- 
tion of the air; anil (3) mechanical disintegration by air 
currents. Putting aside the oxidation of the air, the lite 
of carbons of different diameters increases in proportion to 
their sectional area. To increase the conductivity of the 
carbons Ihey are sometimes plated for about nine-tenths of 
their cylindrical surface with a thin layer of copper, the tip 
only being left Uficoated. The primary object of the plat- 
ing is to reduce the contact resistance of the carbons. A 
copper-plated carbon would seen re to the Spectrum the rates 
of vibration of copper in addition to that of carbon. 
1 a the copper lines are sharply defined; even on one side, and 
the spectrum, therefore, has a peculiar appearance. In the 
Bunsen dame cupric chloride produces a hand spectrum 
extending over the whole field with the exception of the 
violet; the same spectrum is obtained with the metal if the 
tlame contains hydrogen chloride. Tin- absorption spectra 
of copper salts are not characteristic, as the compounds pro- 
duce total extinction both tn the red and violet. The addi- 
tion of copper lias no advantage therapeutically. 

With the use of heavier currents from 50 amperes up- 
wards, the carbons become hotter and are oxidized farther 
back from the ends, and, therefore, have longer points. In- 
side of the crater, the positive carbon wastes away by elec- 
trolytic action, and outside of the crater by the action of 
tin- air Upon it. This wasting in an open arc is twice as fast 
for the positive as the negative. The consumption of the 


negative is clue to the oxidization of the air alone, accord- 
ing as its temperature is increased by the carbon particles 
deposited on it, and by the heat reverberated from the crater. 
The shorter the arc, or the closer the positive to the nega- 
tive, the greater will be its heating effect upon it. In very 
short arcs the deposit of the particles of molten carbon or 
graphite is greater than with long arcs, so much so that the 
negative accumulates faster than it wastes away, and a nib 
or second point is formed on the negative which finally 
crumbles away. In the long arc these particles of boiling 
carbon float about and serve to reflect and refract the rays 
of light, thereby increasing, as has been pointed out, the 
violet and ultra-violet frequencies. Carbon that has been 
exposed to the temperature of the arc is turned to graphite. 
The tip of a negative will write as will a pencil, and the 
positive also shows some graphite. 

The Arrangement of the Carbons of Arc-Light Mechan- 
isms and Reasons Therefor. — The arc mechanism may be 
arranged with the electrodes in a perpendicular or vertical 
position, horizontally or at an angle varying from an obtuse 
to a right angle. In vertical arcs, the positive carbon is 
usually the upper one. The reason for this lies in the fact 
that the crater formed in the positive carbon by the volatili- 
zation of the carbon is the source of the most intense 
light, and by placing the positive carbon above, the light 
is thrown down. This is as a rule desirable for purposes 
of illumination. If it is desired to illuminate the space 
above rather than below the arc, the position of the carbons 
is reversed. In a horizontal arc, as in a marine search- 
light, for example, where a Mangin mirror or reflector 
is placed at the back of the arc, the positive carbon is 
placed in front of the negative, thus directing the arc 
toward the reflector and away from the object upon which 
the illumination is to fall. The reason for this is that all the 
emerging rays shall be parallel, in which condition their 
intensity is theoretically the same at any distance, but prac- 
tically not, owing to unavoidable dispersion, due to the size 



of the light-emitting surface, aberration in the reflector, and 
the refraction and absorption of the atmosphere. With tin* 
crater turned toward the front of the searchlight, all of its 
rays that did not strike ihe reflector would he divergent in- 
stead of parallel. The carbons in searchlights, as in projector 
lanterns, locomotive headlights, may also he inclined at an 
varying Irons an obtuse to a right angle. When the 
ii3 are inclined away from an object so that the maxi- 
mum rays at an angle of about 45°, from the axis 
oi 1 lie positive carbon will be directed nearly horizontally 
at the point to be illuminated. This method is used, as will 
be seen in discussing apparatus and arrangement of 
mechanisms for therapeutic work. Besides being tilted the 

upper carbon is oil en >ei back somewhat <»ut of line with the 
negative, which brings the crater at an angle without tilting 
the carbons. Are lanip mechanisms so arranged are ffifj 
difficult to feed automatically and therefore are apt to 
be hand-fed lamps. In the various arc-light mechanisms in 
use for therapeutic work, the arrangement of the carbons 
differs. In the lamp used in the Finsen Light Institute at 
* openhagen, with the Finsen tube, the carbons are arranged 
vertically and the tube, with its condensing lenses of quartz, 
is placed radially to this powerful arc, so that the light 
from the arc impinges upon the lens at the proximal end at 
an angle of about 45°. The well-known London Hospital 
lamp, originally the Lortet ct-Genoud lamp, has the car- 
bons inclined at an angle of about 45 , This is theoret- 
ically the best position of the carbons, for the reason that 
the energies of the tight of the arc proper, the vapor light, 
or violet mist is brought more directly opposite the quartz 
of the water-COoling chamber and is therefore carried 
more directly to the patient, In a vertical arc, the 
bOQS may be "staggered" or the Upper one set back some* 
what out of line with the negative, as indicated, which 
brings the crater at an angle the same as when the car- 
bons are placed at an angle, and renders it possible to 
utilize the light of the arc proper at its full value. The 


objection to this position of the arc in therapeutic work 
is the necessity of using a hand-fed instead of an automati- 
cally fed mechanism. In the small iron electrode lamps, 
the electrodes are placed vertically. The construction of 
these mechanisms is such as to preclude any different posi- 
tion of the contacts. 

Regulators of the Electric Arc. — For therapeutic work, 
as well as for the purpose of illumination, it is necessary 
that the light must be continuous. To this end it is not 
only essential that the current should be constant, but 
that the distance of the carbons must not alter. 
Therefore it is necessary to use some arrangement by which 
they may be brought together in proportion as they wear 
away. Two methods are used for this purpose : ( I ) hand 
regulators and (2) automatic regulators. The first is an 
arrangement of a screw, to be adjusted by hand and which 
regulates the position of the carbons in relation to one 
another as they are worn away. For therapeutic work this 
is unquestionably the most delicate method, but possibly 
necessitates more careful attention on the part of the opera- 
tor than the second or automatic-fed mechanism. 

Automatic Regulators. — There are two distinct classes of 
mechanisms employed in arc lamps : ( 1 ) those which main- 
tain constant the distance between the electrodes, but do not 
keep the position of the arc fixed, and (2) those which not 
only keep the distance between the carbons fixed, but which 
also maintain fixed the position of the arc. 1 

In the first class of mechanisms but one carbon usually 
the upper or positive carbon is fed or moved; in the other 
class, both carbons are moved and in this case since the 
positive is consumed more rapidly than the negative the 
relative motions of the two carbons must be different. To 
the first class of mechanisms belong the ordinary type of 
arc lamps employed for street lighting. These same arc- 
light mechanisms are used therapeutically in arc-light cabi- 

Houston and Kcnnclly 


To the second class belong various projectors, search- 
lights or other apparatus employing reflectors or lenses. 
In the latter instance it is necessary that the arc shall be 
maintained al the focus of the reflectOf or lens. This is the 
case with the marine searchlight mechanism in use for 
therapeutic work. The feeding mechanism then in any 
form of arc lamp, in order to insure continuous operation 
must comply with the following 3 conditions: (1) It 
must bring the carbons initially into contact. (2) It must 
thru separate the carbons to a suitable distance and main- 
tain this distance. (3) It must cause or permit the car- 
bons to approach when consumption or burning has ren- 
dered their separating distance too great. 

There have been many arc-light mechanisms devised, 
and there are many in extended use. While they present 
minor differences, fundament ally they are practically the 
same, for all lamps suitable for series connections ; that is 
to say, an electro-magnet in the main surface operates a 
mechanism which effects the separation of the carbons, 
while another electro -magnet placed in the shunt circuit, 
effects an approach of the carbons. 

The Gases of the El ec trie Arc. — With a powerful 
current a very dull incandescence is observed, accom- 
panied by a bluish lambent flame, over the ends of the 
carbon electrodes when the gap is from i to j of an 
inch in length. The origin of this flame is exactly 
the same as that which may he observed playing over a hard- 
coal fire, when by reason of an insufficient supply of air it 
has not reached full incandescence. This is due to the 
burning of the carbon vapor in the oxygen of the sur- 
rounding air. Chemically, carbon undergoes two distinct 
forms of oxidation, producing carbon monoxide, as in the 
case of the hard-coal fire, and also the ends of the carbon 
in the electric arc ; and a second but more complete oxida- 
tion, carbon dioxide or carbonic acid. It is believed that 
in tbe interior of the are no oxidation of carbon vapor 
occurs, not only because the vapor fills this interior space, 


and, therefore, displaces the air, but because the tempera- 
ture of the disengaged vapor is so high that it is above 
that at which carbon monoxide can exist, without dissocia- 
tion or separation into carbon and oxygen. 1 The inner 
portion of the arc stream which consists of a violet hub of 
incandescent carbon vapor, is surrounded by a thin non- 
luminous portion where the combination of the carbon with 
the oxygen of the atmosphere in dark flame takes place to 
form carbon monoxide (CO). As the temperature is above 
that at which the monoxide of carbon can exist without dis- 
sociation into carbon and oxygen, it follows that there is 
such a dissociation or separation and the oxygen thus re- 
leased is, in turn, enveloped by a layer of luminous flame 
in which the carbon monoxide burns to carbon dioxide 
(C0 2 ). Besides this combination there is an action on the 
nitrogen of the air by oxygen set free and uncombined form- 
ing an oxide of nitrogen. From the characteristic odor as 
well as from the powerful deodorizing or disinfecting 
nature of the arc when in activity, it has been supposed that 
ozone was given off to some extent during the activity of 
the arc. This is not the case. The odor is attributed to 
the presence of small quantities of hydrocyanic acid gas. 
None of these gases arc given off in sufficient quantities 
where the voltage of the arc does not rise above 55 in air 
to be injurious. On the contrary, judging from clinical 
results they would seem to be helpful, for as will be shown 
in the use of the arc therapeutically, voltage 45, two in 
series 15 amperes each, there is evidence of an immediate 
oxidizing action upon the respiratory mucous membranes, 
when patients with bronchial asthma, bronchitis, tuber- 
culosis pulmonalis or catarrhal colds are exposed to their 
activities. So true is this that the author has for the past 
11 years used an electric-arc cabinet, constructed in such 
a way as to permit the patient to lie fully within it, head as 
well as body, with excellent results. Whether there is an 

l Houston and Kennelly, Electric Arc Lighting, pp. 21-24. 


anae s th e tic effect produced upon the mucous membranes by 
tlu- action of carbon dioxide is an open question. The relief 
from cough is established at the first exposure and persists 
with the continuance of the treatment at successive 
periods of lime, nor is there ever any indication of any 
irritating or untoward effect upon the mucous mem- 

The production of the oxides of nitrogen in air by so 
active arc has been fully established by Charles S. Bradley, 1 
both by e xperim ental Work and successful practical appli- 
cation of the principle, to the commercial production of it- 
inospheric products. This is justification for the belief that 
the outcome of all the combinations and recombinations 
which take place during the burning of the arc is the forma- 
tion of oxides of nitrogen in the air. The same is true of the 
disruptive discharge from a static machine or a high ten- 
sion coil, but with that there is also a production of ozone 
while the brush discharge produces ozone and no oxides of 
nitrogen. Therefore, if it is desired to produce ozone the 
brush or eonvective discharge is efficient, if oxides of nitro- 
gen, the electric arc, while the disruptive discharge is un- 
suitable for the one or the other. If it be true that there is 
a momentary production of ozone (due to liberation of 
owgen molecules, which temporarily unite with O t ) at the 
breaking of an arc, i.e., when the physical conditions of the 
arc correspond to the condition of strain in the air, before 
the actual lightning discharge, there is then a reason for the 
belief that there is more ozone produced by an alternating- 
current arc than by a direct one t for by reason of the alter- 
nations there is a constant breaking of the arc. 

Negative Corpuscles, Carriers of Negative Electricity 
from Incandescent Metals and Carbon, their Relation to the 
Arc Discharge. — From incandescent metals and carbon there 
is a very rapid escape of negative electricity, J. J. Thomson 2 

'PtTSMnal comrmnih mi> >n 

3 J. j. Thomson: Conduction of Electricity through Gases, pp. 
164, 165. 


in his investigations on the conduction of electricity through 
gases, shows that this electrification from a hot wire is con- 
veyed by the same carriers as the cathode rays, i.e., by "cor- 
puscles," "those small negatively electrified bodies which in 
all of the phenomena investigated by him, were found to act 
as carriers of negative electricity in high vacua.'* 

"Corpuscles" are projected, according to his theory, 
from an incandescent metal or glowing piece of carbon, the 
rate of emission being very much greater with a carbon than 
with a platinum filament, amounting in the former when it 
is at its highest point of incandescence, to a current equal to 
several amperes per square centimetre of surface. In like 
fashion the sun and, probably, any luminous star is to be 
regarded as a source of negatively electrified particles, which 
stream through the solar and stellar systems. When cor- 
puscles moving at a high speed pass through gas, they make 
it luminous. In the same fashion when the corpuscles from 
the sun meet the upper region of the earth's atmosphere, 
luminous effects are produced. These corpuscles are dis- 
seminated through metals and carbon, not merely when they 
are incandescent, but at all temperatures ; they arc so small 
that they are able to move freely through the metal, and may 
thus be supposed to behave like a perfect gas contained in a 
volume equal to that of the metal. The corpuscles are at- 
tracted by the metal, so that to enable them to escape into the 
space surrounding it they must have sufficient kinetic energy 
to carry them through the layer at its surface, where its at- 
traction of the corpuscles is appreciated. 

If the average kinetic energy of a corpuscle, like that of 
the molecule of a gas, is proportional to the absolute tem- 
perature, then as the temperature increases, more and more 
of the corpuscles will be able to escape from the metal into 
the air outside. 

The phenomena connected with the discharge of elec- 
tricity from incandescent bodies Thomson 1 found to indi- 

\J. J. Thomson: Conduction of Electricity through Gases, pp. 
424, 425. 



cate a different explanation of the arc discharge. An incan- 
descent body, luch as a piece of carbon, even when at a tem- 
perature far below that of the terminals in the arc. dis- 
charges, as has been stated, negatively electrified corpuscles 
at a rate corresponding to a current of the order of an am- 
pere per square centimetre of hot surface. If a piece of 
carbon were maintained independently at the same high 
temperature and used as the negative electrode, a current 
could be sent thmngh the gdfl to another electrode, win 
this second electrode were hut or not. Suppose the anode 
to be cold, then the current would lie entirely carried by 
negative ions, these would cause the electric force to in- 
- as we pass from the cathode to the anode resulting if] 
a rapid increase of current with the potential difference. 
If the anode then becomes hot and has some gas in contact 
with it which can be ionized, yielding a supply of positive 
ions, the current will no longer be carried entirely by nega- 
tive ions, though inasmuch as the velocity of the negative 
ion at these high teinpe rat tires is very much greater than 
that of the positive, by far the larger part of the current is 
carried by the negative ions. The distribution of pot- 
between the electrodes is very much modified, however, by 
the presence of the positive ions. The latter diffuse into 
the region of the discharge until they are sensibly equal in 
number to the negative ions ; when this is the case there is a 
very uniform electric force between the terminals, except 
the electrodes. The distribution of potential be- 
tween two hot electrodes bears a great resemblance to the 
distribution of potential between the terminals in the arc 
discharge. By the high temperature in the interior of the 
metal, an electric force is produced which drives the electrons 
toward the anode* 

It is believed by Thomson that the arc discharge is 
similar to the discharge between two incandescent terminals, 
the Oltly difference being that in the flame the temperature of 
the terminals is maintained 1 >\ independent means while in 
the are it is maintained by the work done by the discharge 


itself, which requires that the potential difference between 
the electrodes also the current passing should not sink 
below certain values. On the other hand maintaining the 
temperature by external air, the smallest potential difference 
is required to send a current. 

Regarding the arc discharge from this point of view 
then, the cathode is bombarded by the positive ions, which 
maintains its temperature at such a high value that nega- 
tive corpuscles come out of the cathode. The anode is bom- 
barded by these negative corpuscles which carry by far the 
larger part of the arc discharge and is thus kept incandescent. 
They also ionize either directly by collision or indirectly by 
heating the anode, the gas or vapor of the metal of which 
the anode is made, producing in this way the supply of posi- 
tive ions which serve to keep the anode hot. The essential 
thing in the arc discharge is the hot cathode as it has to sup- 
ply the carriers, negative corpuscles, of the greater part of 
the current in the arc. As the metal or the carbon terminal 
of an arc volatilizes, the arc goes through a mixture of the 
vapor of the metal and the air. The negative corpuscles of 
Thomson serve to produce on ionization of this gas or 
vapor and of the air itself, a condition which to the author's 
mind is comparable to the action of the negative corpuscles 
emitted by the glowing carbon of the photosphere of the sun 
upon its gaseous envelope. 

The arc is deflected by a magnetic field in the same 
direction as a flexible conductor would be if it carried a cur- 
rent flowing in the same direction as that through the arc. 

The curved course corresponds to a longer path and the 
effect of the magnetic field on the potential difference is of 
the same character as an increase in the length of the arc, and 
just as it is possible to extinguish an arc by increasing its 
length, so the arc can be blown by the application of a strong 
magnetic field. 1 

The ionic theory of the electric arc has been investigated 

'Thomson, p. 431. 



to a considerable extent by Stark. 1 In order to make the 
matter more simple he began his investigations with the 
mercury arc which is longer than the carbon. Four distinct 
parts are distinguished, viz : ( i ) The brilliant brush issu- 
ing from the white hot depression in the cathode, (2) the 
dark space, ( 3 ) the positive light column and (4) the anode 
layer. The arc light involves the evaporation of the cathode 
or negative carbon as has been stated, but this is not neces- 
sarily involved by the glow discharge. Nor is it essential 
that the anode should emit vapor, as is the case in the car- 
bon arc. 

In all gaseous discharges, electrons, positive atomic ions, 
and molar ions have to be distinguished. 

Negative electrons play a very important part in a Bun- 
sen flame. They are even more predominant in the higher 
temperature of the electric arc, as is shown by the suscep- 
tibility of the arc to magnetic deflection and the readiness 
with which it follows every variation in the current. This 
is owing to the great nobility of the electrodes. The impact 
of the electrons produces positive and negative ions from 
neutral molecules at the anode and in the positive light. In 
the glow discharge the phenomena are reversed, %vhereas in 
tliL' arc the negative electrons are produced from the cathode 
by electrification, and not from the gas by ionization. The 
presence of ultra-violet light, but most of all the high tem- 
po ratti re of the cathode, favors the ejection of electrons from 
the interior of the cathode. 

The anode on the other hand must be hot, otherwise it 
could not supply the positive ions which keep the cathode 
hot. If a third electrode were put in the arc acting as 
one of the anodes, then the discharge may be regarded as 
having two anodes. As one is sufficient to keep the cathode 
hot, the arc can pass to the other anode even although it is 
cold. A small portable lamp, with iron electrodes for thera- 

'Am. der Phv^k N<* u; London Elect.* Otc 4- 1903; Electrical 

World and Engineer, January 2, i<ku 


peutic work, is constructed on this principle, and is known 
as the Reiniger, Gebbert and Schall lamp. 

The negative corpuscles, therefore, play an important 
part in the activity of the arc, acting ( i ) by carrying the arc 
discharge, (2) bombarding the anode to incandescence, (3) 
ionizing directly by collision, or indirectly by heating the 
anode, the gas or the vapor of the metal, of which the anode 
is formed, producing in this way (4) the positive ions, which 
serve to keep the cathode hot. 

Metallic oxides project more electrons at high tempera- 
tures, and hence the arc, which requires a liberal supply of 
electrons is more easily formed of the oxide than of the pure 

The negative electrons, given off at different rates, evi- 
dently for different metals, influence the potential differ- 
ence. 1 

Of the constants m and n in Frohlich's formula, as 
measured by Frohlich himself and Edlund, Lang, 2 Gross, and 
Shepard, Nebel,. Arons, 3 Luggin for carbon electrodes in air 
at atmospheric pressure, m is about 39 volts, varying some- 
what, however, with the size and purity of the carbons. It 
is diminished by soaking these in salt solution. The value 
of w, as given by different experimenters, varies consider- 
ably. This may and probably is due to their having used 
currents of different intensities, as Mrs. Aryton has shown 
that n depends upon the current, for as the current increases, 
n or the potential difference diminishes. When metallic, 
instead of carbon terminals are used the value of n 
or the potential difference depends upon the metal. As a 
rule this is greater the higher the temperature at which 
the metal volatilizes. The following table gives the value 
of the potential difference in volts for different sub- 
stances : 4 

'Thomson, J. J. Conduction of Electricity through Gases. 
*Lang: Wicd. Am. XXXI.. p. 384. 1W7. 
•Arons: Wied. Am., p. B, 1896. 

Linn [ km s 

C = 35, Pt = 27.4, Fe = 25, Ni 5* 26.18, 

Cu — 23.86, Ag sa 15.23, Zu = 19.86, Cd == 10.28. 

Lecher 1 gives Pt — 28. he — 20, Ag = 8. Arons found 
that hut 12.8 volts were required for Ag, but in this case 
the fail of potential along the arc itself was very small 
With some of these metals used as terminals the arc is inter- 
mittent Iron, platinum ami mercury have been shown to 
give an intermittent arc, while no intennittence has been de- 
tected willi carlxm, silver and copper terminals. 

These potential differences with arcs of different metals 
are mean values, and if the arc is intermittent they may dif- 
fer greatly from the actual potentials during the passag 
the arc. When the different metals arc used for the two 
terminals, the potential difference may depend upon the direc- 
tion of the currents. This is especially true when one of the 
terminals is carbon and the ; it her metal, carbon and iron for 
example, or an iron-cored carbon. The arc passes much 
more readily when the carbon is the negative terminal, and 
the metal the positive one than it does in the opposite direc- 
tion. So true L this that if such a pair of terminals were 
connected up with an alternating potential difference, the 
arc may only pass in the direction in which the carbon is the 
negative terminal, the potential difference being insuffi* 
to drive it the opposite way. Some metals again are non- 
arcing metals; that is, they have a tendency to 140 out, such 
as brass, bismuth and cadmium. A great deal depends upon 
the size and shape of the electrodes, as well as the material 
Of which they are made. Conditions which promote a rapid 
How of heat from the extremities are favorable to the extinc- 
tion of the arc. 

The potential difference depends also upon the pressure 
of the gas through which the arc passes, Duncan, Rowland 
and Todd have shown that for short arcs the potential dif- 
ference increases continuously with the pressure, while fof 
longer arcs there is a critical pressure at which the potential 

'Lecher: Wied Am XXXUL, p. too. it 


difference is a minimum; this critical pressure increases 
with the length of the arc. The arc is affected by the nature 
of the gas ; in hydrogen, for example, it is difficult to get a 
good arc, and this is supposed to be due in part to the more 
rapid convection of the heat from the terminals. 

The potential difference required to produce an arc by 
the use of different metals, both in air and pure nitrogen, has 
been measured by Arons. 1 In the case of silver, while giv- 
ing a good arc in air, none could be obtained in pure nitro- 
gen. This Arons attributed to the absence of any chemical 
combination between the silver and the nitrogen. With the 
other metals used, zinc, cadmium, copper, iron, platinum, 
aluminum, lead, and magnesium, he obtained evidence of the 
formation of nitrites. Copper excepted, the potential dif- 
ferences in nitrogen are smaller than in air, the difference 
being very noticeable in the cases of iron and aluminum. 
In both these instances more active ionization of the air, due 
to their temperature of volatilization, rates of oscillation and 
electrons given off, the noticeable difference of potential be- 
tween these two in air and nitrogen (smaller in nitrogen 
than in air) is to be accounted for. This is not yet clearly 

Arons was only able to obtain arcs in hydrogen by using 
large currents and having the gas at low pressure. Cad- 
mium, zinc and magnesium gave the best arcs in hydrogen. 

As the metal or the carbon terminal of an arc volatilizes, 
the arc goes through a mixture of the vapor of the metal 
and the air, or in the experiments referred to, nitrogen or 
hydrogen, in which the terminals are immersed. This ren- 
ders it difficult to interpret the effect of changes of pressure 
in the gas around the terminals, as the pressure of the vapor 
of the volatilizing metal is not kn^wn. 

It has long been known that air in the vicinity of red 
hot metals is a conductor of electricity, nearly two centuries 
in fact. 

'Arons. Drudes' Annalcn. I., p. 700, iqoo. Quoted from Thorn- 
Son's Conduction of Electricity through 



Iii 1853 Becqtierel* showed that ?ir at a white heat per- 
mitted the passage of electricity even when the potential 
difference was only a few volts. This result was confirmed 
by Blondlot* whose observations went still farther, for he 

proved that air at a bright red heat was unable to insulate 
under a difference of potential as low as 1/1000 of a \<>H 
and that conduction through the hot gas was not in accord- 
ance with Ohm's law. 

Attention was first called by Guthrie 21 to a very charac- 
teristic feature of ionization by incandescent metals, viz., the 
want of symmetry between the effects of positive and nega- 
tive electrification, He showed that a red hot iron ball in 
air could retain a charge of negative, but not of positive 
electrification, while a white hot ball could not retain a 
charge of either positive or negative electrification. 

The Electric Arc a Disinfectant. — An electric arc in 
operation serves as a powerful disinfectant 

The action of the energy of the electric arc spectra upon 
bacteria has been very fully considered, but it would seem 
that there is an effect produced more immediately than 
would follow upon the destructive action of the short and 
high frequencies so active chemically upon bacterial growths. 

Experiments were made many years since with the 
Jablochkoff candles in the Paris sewers for the purpose of 
purifying them. The results were very satisfactory. 

In 1881 Mr, Harold P. P.rown, E. E./ of New York, 
while using Brash arc lamps fnr lighting the basement of a 
store in Chicago, noted that within an hour after turning 
on the current, the odor from the toilets which was at first 
very offensive became entirely neutralised. 

On an excessively hot day the author made the follow- 
ing observation; the refuse barrels which had accumulated 

'Becfjuerel : Annales de Chime et dc Physique, lit., 39, p. 355* 

*B!ondlot: Comptes Rcndus, XCII.. p. 870, 188 r : CIV., p. 283, 

'Guthrie: Phil. Mag. IV., 44<>, P 257, 1873. Quoted by J. J. 

'Personal communicate m. 


in the basement of the apartment house occupied as an office 
over Sunday, prior to their removal Monday morning emitted 
a very unpleasant odor, which ascended and permeated the 
office rooms occupied by the electric-arc cabinet as well as 
rooms to the rear of it. The current operating the electric 
arc was turned on and in half an hour the author returned to 
the room, to find that every evidence of odor had disappeared 
and that the air was perfectly pure, so far as odor was con- 
cerned, while in the rooms more remote from the arc, the 
odor persisted as before. The action was at that time 
attributed to the ozone generated and unquestionably it is a 
factor. There is the nitrous oxide to be reckoned with as 
well, but the effect in all probability is due to an ionization 
of the air. Since then, if for any reason there has been the 
slightest odor in the offices the current has been turned on 
the arc lamp and always with the same result. 

The Mercury Vapor Lamp. 

The temperature inside of the lamp, which depends upon 
the current, diameter and density of the vapor, is not ordi- 
narily very high — a few hundred degrees Centigrade at the 

The most striking feature of the lamp upon casual exami- 
nation, is the color of the light which it emits. This, to 
l>e appreciated, must be seen as it is difficult of description. 
It is spoken of as having a yellowish-bluish green color, the 
nearest approach to naming the color. It suggests to the 
author an opalescent coloring. Spectroscopic examination 
shows the presence of two somewhat faint orange lines, two 
very bright green lines, two bright blue lines, and two faint 
^violet lines. There are no red lines present and therefore it 
is impossible for the lamp to give off white light, as red is a 
necessary constituent of white light. From the orange, 
green, blue and violet present, results the characteristic col- 
oring. Objects which ordinarily reflect red light, like the 
human being, for example, suffer a very remarkable and 
gruesome color distortion. The appearance is ghastly in the 



Die, but is overcome by the use of a specially prepared 
red OT pinkish gauze which is thrown over the lamp as a 
scarf or drapery. This supplies the red frequencies and by 
reason of its preparatory chemical treatment functions as a 
radiant frequency transformer, A tube of red glass would 
permit no tight to emerge whatever, for red glass transmits 
red light only ami there is no red light to transmit. The 
light is extremely rich in ultra-violet waves, richer even than 
the arc light, hut by reason of the glass of the vacuum tube 
there is no possibility of their emergence. It is very rich, 
however, in the visible chemical frequencies, and for this 
reason and also because of its diffusion, it is very valuable in 
photographic work. Its efficiency is estimated at from two 
to three times that of the arc light and from six to eight 
times that of the incandescent light, It consumes less cur- 
rent than the incandescent light. 

It is impractical for applications where compression is 
desired In render a part anaemic. These lamps could V>e sus- 
pended around the walls of a large enclosing cabinet or room 
for general uses, but the author is not prepared to state that 
it would be well to use them in preference to the other 
sources of light if at all. They lack the radiance that renders 
sunlight, the electric arc, incandescent light even, so accepta- 
ble to the anaemic, neurasthenic or tubercular patient as well 
as of such therapeutic value. Rich as they are in ultra- 
violet light, it is of no valne for less than 30 microcentime- 
tres because of the glass enclosing tube. Objections have 
been raised because of the mercury vapor but the author fails 
to see how with this enclosed in a vacuum tube of glass it 
can possibly have any effect. Were tt a quartz enclosing 
tube the ultra-violet would be powerfully in evidence and 
the result from exposure to so powerful a source of concen- 
trated ultra-violet energy might lie productive of untoward 
results. The author has had one of these lamps placed at 
her disposal during the past year but from observations thus 
far made, would not select it as a source of radiant light 
energy for therapeutic work. It can only be stated here as 


an impression received from observations, not supported as 
yet by experimental data, that the absence of the red and the 
diminution in the orange and yellow, in other words, of those 
factors which give the sensation of radiance, is one for 
which its powerful chemical action cannot compensate. 

There is in relation to physiological action and therapeu- 
tic uses of light a need for these long and slow frequencies — 
although in the present state of the biological action of light 
it is not known just what their mode of action is. Function 
they undoubtedly have. It only remains to be elucidated. 
Were the enclosing tube of such size and shape as to render 
it suitable for topical applications, the richness of the light 
chemically could be availed of. 

The following data and the description of the test to 
determine its candle-power were furnished by Professor 
Sheldon of the Brooklyn Polytechnic Institute, in connection 
with the author's committee work on "Radiant Energy" for 
the American Electro-Therapeutic Association. 

Data Concerning the Cooper-Hewitt Mercury Vapor 
Lamps. — An effort was made to determine the candle-power 
of this lamp by making use of an observer who was afflicted 
with color-blindness. His visual characteristics are shown 
by the following facts : He called a bright red glass green, 
and was very positive concerning it. He called a green glass 
brown or red and was not very certain. Blue he termed 
blue, amber was called a light red. A bright red was again 
called brown and he matched a bright red against a muddy 
purple as being alike. 

The prominent lines of the mercury spectrum appeared to 
him as follows : The two orange lines as dark yellow, the 
faint green he could not see, the purple of long wave length 
he considered not as light as Columbia blue, but as blue, and 
the violet of shorter wave length he termed as the same 
color which could be purchased at a florist's. It will thus 
be seen that he is what may be termed red and green color 
blind. When used as a photo- metric observer inJjalanciug 
two incandescent lamps against eft >thcr, Miming 



at the same temperature, making use of a Lu miner Brodhun 
screen be made settings which were practically identical with 
those Hi ordinary observers. 

When balancing the light from an aperture 10 X ^ 
centimetres placed in front of the vapor lamp against the 
standard 16 candle-power lamp he was unable to obtain 
a definite point of balance because of the different color 
qualities, hut at a place where the corn yellow exhibits to the 
ordinary observer about the same depth as the sky blue. 
these colors changed suddenly to the eyes, the yellow 
appearing yellow, but the blue assuming a color he had never 
seen before. 

By holding the green glass in front of his eyes he made 
very precise balance setting; which yielded the following 
results : Through the 20-centirnetre-square opening passed 
luminous flux such as would come from 63.5 candle-power 
sources of 3.18 candle-power per square centimetre. The 
lamp was taking 3 amperes at 7$ volts, exclusive of the start- 
ing rheostat. 

Assuming a uniform distribution of light emanations, the 
tube which is 1 14 centimetres long, and of approximately 2.4 
centimetres internal diameter, will give 870 candle-power, 

It has been suggested that its value in medicine will be as 
a diagnostic agent chiefly. 

As there are no red frequencies any red spot Of) the 
body of a person subjected to its action or any red object 
observed becomes a deep purple. 

Therefore any mild inflammation or rash, either faint or 
more distinct, will become under its influence a distinct pur- 
ple in appearance and an eruptive disease may be detected 
earlier and more clearly than would otherwise be possible. 

The accompanying illustrations show the energy curve 
of different sources of light. The author is indebted to me 
courtesy of Professor Langley of the Smithsonian Institute 
for their use. (See Figs. 2 and 3.) 

The second plate is introduced as showing the amount 
of energy wasted in sunlight, when considered as a luminous 

Jour Curves of Equal Areas, snowing one unit of heat displayed 
successively in heat spectrum of Gas, Electric Arc, 8un and 

Fire- Ply, 

Abscissae, Wave LENGTHS. 

Ordinate*.- Energy as Heat. 

! 8 

i LIMIT* • 
-H*] VI9I91£\ 


Gas Flame Spectrum. 


Electric Arc Spectrum. 


Fig. 2. 



A— Sun-light. 
B-AVe-jty tight. 

Abscissae.-Wave Lengths. 
OnoiNATEs — Luminous Intensities. 


A- Sun-HpM Spectrum* 

B. Fire-fly Spectrum. 

Fig. 3. 



agent only, illustrating at the same time the luminous effi- 
ciency of the firefly spectrum. But as these pages endeavor 
to show, the sun shines not simply for the purpose of illumi- 
nating the darkness, but that life from the elementary forms 
to the higher organisms may exist. 

The Action of Light Encsgy upon Elementary Forms of Life. 

The irritability of a mass of protoplasm of a protozoan of 
the simplest kind is established in a certain manner under 
the influence of light energy. This has been extensively 

Action of Luminous Rays upon a Plastide. — If a beam 
of parallel luminous rays of feeble intensity fall Upon a 
plastide in water* the reactions between the plastide and the 
surrounding medium are favored by the delivered 

in this way. This was studied by Dantic l ( hetntcal re- 
actions are established which are much more active on the 
surface upon which the light falls than on the opposite face, 
hnl feebly illuminated by the light filtered through the mass 
of protoplasm. The plastide is divided into two pan 
to speak, which arc respectively the seat of excitations of 
different intensity. The result of this difference is shown 
b\ a direct action whose beginning and direction can be cal- 
culated by mathematical analysis, for a body of determined 

Phototaxy Positive and Negative. — This theoretical fact 
is verified by a quantity of experimentation done by Sti 
burger, Verwom, Etigelmarm, etc.. bearing upon plastides^ 
diatom*, spores of algae, bacteria. 

*F, Lc Dantic: Materie Viranie, Paris, Mosson quoted hi 
Lercdtjf and Pan our 


The movements vary in direction and the minute mass of 
protoplasm can be drawn out or retracted under the influence 
of a beam of light. In the first instance it is positively 
phototaxic, and in the second negatively phototaxic. On the 
other hand, there are certain plastides that are not influenced 
by light, that is. they are not phototaxic. This latter condi- 
tion may, however, be dependent upon the degree of light 
intensity to which it is subjected. If the intensity is too 
feeble it may appear to be non-phototaxic when such is really 
not the case. 

Leredde and Pautrier pertinently remarked that the in- 
tensity should always be given when positive or negative 
phototaxic conditions are considered. For example, an 
amoeba which will stretch out or contract its protoplasm 
under the influence of feeble light intensity will contract 
itself sharply if the intensity is increased 

In the absence of all phototaxic phenomena it is difficult 
to establish whether or not the protoplasm under considera- 
tion did not react because the light was too feeble. How- 
ever, all protoplasm can be considered as phototaxic, either 
positively or negatively. 

If an infusion containing various plastides be exposed to 
diffused light, certain among them will be seen to gather 
themselves into the brightest part, while others will remain 
in the shade. 

It is in this way that Kngelmann takes in a trap bacteria 
in a bright spot from a liquid kept in the dark. From a 
close study of this phenomenon it will be seen that it is not 
only the passage of light in obscurity which exercises an 
excito motor action upon protoplasm, but also difference ot 
light intensity. Purple bacteria are particularly sensitive 
to this mode of action. If the intensity of the light illumi- 
nating the preparation be diminished, when examining them. 
the rotation of their bodies is reversed and they extend 
abruptly to a distance equal to ten or twelve times their 
length. Any spot thus illumined in a tube or receptacle con 
taining the bacteria, becomes a veritable trap for them. They 



readily enter the brightest spot which attracts them, but it 
is impossible for them to leave it, for in passing into the 
dark peripheric zone, they are sharply thrown kick into the 
hi zone, just as iron filings arc brought into relation 
with a magnet, fur example. 

In his experiments Engelmann illuminated the centre of 
the drop at water, upon which he was operating, then fixed 
and colored the mass of bacteria which had quickly as- 
sembled there. He obtained in this wav what he calls a 
bacteriograninu\ In this way he preserved the image of the 
space in which the bacteria were caught in a trap 

The excitu motor action ol light is very clearly shown 
on purple bacteria. J'hey are one or the best examples, and 
are sensitive to the luminous excitant alone. L pun ilhinu 
nation they take on a state ol continual motion or, as termed 
by Leredde and 1'autrier, a period of photokmetit induction 
When the light is removed they return to a state of complete 

Among the miscellaneous algx positive phototaxy >- 
equally frequent. 

In his study of the movements of diatoms Engelmanii 1 
shows the cessation of movement when he placed them in the 
dark sheltered from oxygen and recovery of the same with 

This phenomenon is complex, for it is not alone the pres- 
ence of light, but it is also i\\]c io the consumption of oxygen, 
which the\ are unable to appropriate in darkness. In the light 
on the other hand the decomposition of the ambient CO, by 
their coloring matter furnished them at the same time with 
the assimilable C. the oxygen necessary to their movements* 

It was observed in the closteria, a unicellular alga, of 
the group of desmidia, fringed at both extremities that 
when placed in a crystal receptacle upon which the beam of 

'Fftuger's Anli Vol, XXIX , 1N79. Ueber Reizung contractflcn 
protopla mi durch plotsltchc Beleucbtung und Engelmann Leber 
Licbt und HirbenpercepUon niederster orgamsmea IMluger s 
Arch. Vol XXIX 


light is directed, the alga is seen to lean itself upon the bot- 
tom of the receptacle by one of its extremities, and then place 
itself in such a position that its axis coincides with the direc- 
tion of the incident light. 

It the incidence of the rays of light be suddenly varied 
the alga pivots itself anew upon its extremity, which sustains 
it and goes again to place itself in the axis of the luminous 

At the end of a certain lapse ot time, from 6 to 8 
minutes, the alga executes a veritable "pirouette," and the 
extremity which served as the point d'appui becomes free and 
directs itself toward the source of light This shows that 
there is then a true phenomenon of polarity and of alternate 
polarity. Pleurotenium and the Micraserias Rota also ex- 
hibit the phenomenon of constant or alternating polarity. 

The zoosphores of the algae are equally phototaxic. They 
are drawn toward the luminous source by placing themselves 
in the direction of the incident ray. but turning always to- 
ward the latter, their non-ciliated extremity. 1 

With pluricellular alg.x, the protoplasm in the interior 
of the cells exhibits a true phototaxy. as in the case of the 
vaucheria, where the grains of protoplasm charged with 
chlorophyll disjwsc themselves in two bands perpendicularly 
to the direction of the incident ray, or in the case of the 
mesocarpus in which each cell is terraced following its axis 
by a protoplasmic plate charged with chlorophyll which, 
under the influence of the light energy, turns itself so as to 
be perpendicular to the radiation. 2 

Myxomycetes, referred to under the action of light upon 
vegetable organisms, are either positively or negatively 
phototaxic according to the degree of light energy. A light 
of feeble energy excites the stretching of their protoplasm 

^Strasburger : Wirkung des Lichtcs und der Warmc auf 
Schwarmsporcn. Jena, 1878. Also, Stahl : Ucbcr den Eintluss des 
Lichtcs auf die Bewegungs crscheinungen der Schwarmsporcn 
Verhand. der physic, medic. Gesellschaft. in Wurzburg, t. XI, 1878. 

"Stahl : Botanische Zeitung, p. 297. 1880. quoted by Lereddc and 


I ii.ll f ENERGY. 

and extends them ; one of tnediitm energy leaves them in* 
different; but a tight of intense eneigj them to run 

or to retract sharply with formation of granules in their 

The lYlotnyxa palustris i> an example of negative photo* 
taw This curifais nliM-rvatiuii w h\ Ingelmann. 1 

The pelonivxa is a rhizopod and is analogous to tin mi 
which is found m the shade at the bottom of ponds eon* 
ocated in tlie slime. Its protoplasmic body is rough, heavy 
and bare. It advances by putting forth fht pseudoj 
Abandoned to itself, it progresses by movements of repeti- 
tion, taking an elongated form and following a certain direc- 
tion, hut always the same. I Fpotl i Kposure to light it 
in a i rids after the granule streaming h;is ceased and 

takes the form ol a hall. If a weak light is maintained slow 
tnents are again to b^ seen When the darkness is <h^ 
sipated by the gradual coming on ot daylight there is no 
irritant action. Mam myxomycetes comp rt themselves in 
an analogous fashion 

Rowers of tan dee from a bright light, which causes them 
to retract, Strasburger* picturesque!) demonstrated the 
action of light on the plasniodia of cethalium ; under the 
influence of a feeble lighl he was iblc to call it to the sur- 
face of a tan ditch, and upon suddenly increasing the bril- 
liancy of the light it was made to rebur) itself in the ditch. 
In the light they develop short, compressed projections, with 
dark, long, thin, narrow prOCC! 

Hofmeister, 1 in his studies upon the role of light in the 
relation to myxomycetes, observed lhat the CEthalium sep* 
ttcuni tied from the lighl, and always in the direction of the 
light rays. This is illustrative of the negative heliotropisrn 
of these bodies. 

The I'holada daclyle, a marine moll US k observed by 

'Eiigchiiann : Ucbet Resztwg Coittractilen Pi las durch 

plotztiehc Beleuchtung Pfliigcr's Arch. Vol XIX. 
'Quoted by Lcredtle and Pan trier 
'Hofmeister ; Uk- Lehre von tier PBanzenzelle. 


Raphael Dubois, has been found to give evidences of photo- 
tactism in that part of the animal's body which is the seat 
of the dermatoptique vision. These phenomena seem to in- 
dicate that light in these instances acts in the same way as 
do artificial irritants. 

Transformation of Form under the Influence of Light 
Energy. — The action of light energy upon these elementary 
forms of life is not confined, however, to excito motor 
phenomena, abundant as these are, as is evidenced by the 
contraction and extensions of protoplasm. The arrange- 
ment of the protoplasm of amoeboid cells, amoebae, rhizopods, 
infusoria is markedly changed by exposure for any length of 
time to light or darkness as well. The action is then upon 
the form, producing modifications which are alike durable 
and definite. By its action the properties of protoplasm also 
may be completely modified and caused to assume new forms. 
These phenomena have been fully investigated by Brefeld 1 
upon the Mucedines, also by Living 2 and Laurent. :{ 

Brefeld's work was carried out upon the Coprincs, and he 
concluded that for the Basideo-Mycetes the development in 
light and darkness is very different. In darkness the devel- 
opment is bad, the head shortens, the foot is enormously 
elongated also. 

The organs of fructification appear only in the light, in 
the darkness the mycelia are sterile. 

Laurent's studies were upon two of the Ilyphomvcetes, 
the Dematium pullulans and the Cladosporium herbarum. 
He was able to derive the first from the second by sowing 
some spores of Cladosporium into must (mout) of beer and 
exposing them to the action of solar light energy. After 
some days of insulation these spores, transported into a new 
must of beer, developed growing forms of Dematium. They 
not only changed form but properties as well : the Clado- 

a Brefeld : Botanischc UnterMiclmngen iiber Schimmelpilze. 
*Elving: Studien iiber den Einwirkung des Lichtes auf die 
Pilse. Hclsingfors, 1890. 

*Laurcnt : Annales de l'lnstitut Pasteur, 1888. 



sporium being exceedingly aerobic, while the Dematium can 
live in anaerobia. 

By the sowing of some spores of Aspergillus glaueus in 
must of beer exposed to the action of solar energy, Giving 
obtained three kinds of yeast forms. These returned to 
dark; ,e in their turn some new v ,i-t forms, which 

were not developed after the type of Aspergillus, but after 
the type of Pen ici Ilium. This latter type was definitely fixed 
and was uniformly produced in subsequent generations. 

Passage of Aerobic Life to Anaerobic Life under the 
Influence of Light Energy. — This phenomenon is observed m 
the purple bacteria as well as the motor phenomena described 
under the action of light. It will be recalled, movements are 
established upon their passage from darkness to tight and 
upon their return to darkness, complete immobility. There 
is also a true modification of vital conditions, i.e., a passing 
alternately from the anaerobic state to the aerobic state and 
inversely. 1 

The Bacterium-Photo-metricum, studied by Engelmann 1 
is the type of the lx\st known of the purple bacteria. This 
micro-organism is exceedingly sensitive to the stimulus of 
light energy. So long as it is exposed to the light it pro- 
pels itself swiftly about in the drop of water by the aid of 
the scourge- like thread which is found at the end of the 
bacterial body. Upon its return to darkness the movement 
of the thread gradually ceases and the bacterium remains 
motionless, to be stimulated again, however, to fresh move- 
ment under a renewal of the light energy, 

It was observed upon examination in the drop, covered 
w T ith a cover glass under the influence of a very feeble light, 
to approach the borders of the plate; while in a stronger 
light it remains collected in the centre of the preparation. 
In this latter instance it is very far from the oxygen. 
In the first instance the condition is the same in the diffuse 

'Lmdde and Pautrier. 

*Archiv. f. d. ges> Physiologic XIX., p. I. and Handbuch der 
Physiologic, Vol L, p. 370. 


light as in the dark and there is need of a source of oxygen 
in order that it may live, hence it seeks the edge of the 
plate ; in the second on the other hand, when exposed to the 
bright light, by means of its coloring matter, which is sup- 
posedly similar to chlorophyll, it is enabled to find the nec- 
essary oxygen in the decomposition of the ambient carbonic 

Action of the Different Frequencies of Light Energy 
Upon Elementary Life. — Thus far the action of the total 
light energy has l>een studied but certain investigations have 
been made, showing that there is a difference in effect from 
the different frequencies of the spectrum. This is illustrated 
by the following interesting experiments of Verworn. 1 

Verworn examined with a microscope a ciliated in- 
fusorium, the Pleuronema chrysalis, which ordinarily is in a 
state of repose, that is immobile in water without ciliary 
movement. When under examination, if the diaphragm of 
the microscope be raised, the infusorium exposed to the 
action of light appears to leap impetuously, after a period 
of one to two seconds or latent period of excitation. 

Verworn analyzed the influence of the different frequen- 
cies by interposing l>etwccn the source of light and the plate 
of the microscope colored liquids, the transparency of which 
to the various frequencies had been determined by sj>ectrum 

He found that the maximum effect uj>on the leaping 
movements was obtained by the action of the blue and violet 
frequencies. To obtain the same effect where tin* thermal 
energy was utilized, it was necessary to have recourse to in- 
tense solar light, concentrating the energy by means of a 
concave mirror. Fretind states that the same effect can be 
produced with intense heat rays. 

The Action of Light upon the Ciliated Corpuscle. — 
Bergel has carefully studied the effects of light and dark- 
ness upon the movement of the ciliated corpuscle in the fol- 

'Allgcmcinc Physiologic Jena, 1895. 

, 3 8 


ng manner : The microscope was placed upon an obser- 
tratioa table within a dark cabinet This cabinet was per- 
fectly closed save for two openings* The one when illumi- 
nated was for the observer but when it was desired to shut 
off the light it was carefully darkened by curtains. < >pp 
the microscope was another opening which could at will 
either he closed or exposed tO direct sunlight, Then hy plac- 
ing a ciliated corpuscle in motion under the microscope and 
darkening the window permitting the light i«> fall upon it, 
the motion of the corpuscle could be seen on inspection to 
grow slower and slower until it finally ceased. The more 
rapid and energetic the vibrational aetivit) of the corpuscle 
before the window was darkened, the lunger the period of 
activity of the corpuscle in the darkness, until it finally be- 
came motionless and vice Vtf$a; the slower and weaker the 
Vibration Of the cilia the shorter the time np to the cessation 
Of all motion. But on the contrary, when a corpuscle which 
had kept in the dark and showed no motion whatever, was 
exposed to the brighl daylight again the oscillation recom- 
menced after a latent period, depending upon the duration 

of the exposure to darkness. The longer the corpuscle 
remained in the dark after it had become motionless the 
r it continued in a quiescent state before resuming its 
oscillations. When the corpuscle was kept too long in the 
dark it showed every evidence of fatigue. This fatigue was 
also noticed when the experiment was repeated several tunes. 

These experiments indicate not only a direct action on the 
ciliated epithelium of the respiratory tract and the necessity 
for light energy in respiratory pathologies, but illustrate as 
well the physical effect of the oscillating swing of light 
vibrations on atomic motion. At least tins is the writer's 
interpretation of these very interesting experiments, nor do 
the phenomena produced admit of any other in the light of 
physical laws. 

It is stated by Freund that, according to Uskoff, the 
ciliary movement of the epithelium of the oesophagus is 
equally swift in red and in violet light, but that it is sus- 


pended if red light is substituted for previously acting violet 
light. Even among the ciliary infusoria, isolated specimens 
are found whose movements are stimulated b\ light. 

Strassburger and Miguel have demonstrated that the 
phototaxic sensibility of the alga?, of their zoospores, of the 
protoplasm of the Vauchcria or of the Mesocarpus is not 
brought into action by all the frequencies of the spectrum. 
The active frequencies arc the blue, indigo and violet. The 
red and infra-red have absolutely no action. 

The phototactic movements of the plasmodia of Myxomy- 
cetes are also under the influence of the most refrangible 
frequencies and are unaffected by the other frequencies of 
the spectrum. The bacterium Photo-met ricum of the purple 
bacteria group is an exception. Engelmann 1 found upon 
examination of a drop of liquid containing a great quantity 
of these bacteria upon which a solar spectrum was projected 
that they accumulated with a particular predilection at cer- 
tain points corresponding precisely with the absorption 
bands of the bacterio-purpurine. that is in the infra-red and 
in the orange and yellow. These therefore were the frequen- 
cies necessary to excite movement in the bacillus photo- 
met ricum. 

Thus far it has been shown that the movements of these 
bacteria are possible only if the oxygen necessary to them is 
furnished by the decomposition of the ambient O \. through 
the intermediary of the coloring matter which impregnates 

It will be seen as with plants that the frequencies most 
useful to them are those which correspond to the absorption 
bands of chlorophyll. The conclusion is therefore permitted 
that the bactcrio-purpurpine plays for the purple bacteria a 
role analogous to that played by chlorophyll for plants and 
the predilection of these bacteria for the red frequencies are 
explained by a functional adaptation. 

'Bacterium PlmtniiK'tricuni. Kin Boitrau zur vorRleiclicndrn. 
Physiologic des Liclit unci FarN»"*'tins, Pfluger's Archiv.. Vol. 



Lcredde and Pautrier in reaching this conclusion, regret 
that the studies and experiments of Laurent and FJvirrg 
upon the change of form and of function under the influence 
of light were made only under tlu j influence of the total light 
energy and that they did not see fit to analyze the action 
under the influence of the different frequencies. 

Summary. — From a careful review of th< interest- 

ing observations of Engelmanm Laurent) Strasburger, 
tT, Brefeld, etc it is clearly evidenced that it is the 
blue, indigo and violet frequencies which are the effective 

By the action of light, and especially of the more refran- 
gible frequencies, a series of phenomena arc produced at the 
lei ■<■! of the protoplasms : 

(i) An excito-motor action, i.e., the extension of the 
various movements of protoplasm. 

t) An influence on the growth and reproduction of the 
mycelium of the algae, 

(3) An extension of forms in one species lasting modifi- 
cations faithfully reproduced by successive generations. 

(4) The concurrent establishment of a complete over- 
turning of the conditions of existence to the point of per- 
mitting an exclusively aerobic organism to become anaerobic* 

Tn a study of the general physiology of the elementary 
forms of life, concludes Leredde and Pautricr, 1 the influ- 
ence of light assumes an important place. The excito motor 
phenomena are the best known and studied. To produce 
them the action of the indigo, violet and ultra-violet fre- 
quencies are required. 

'Photobiologic and Phototherapy, Leredde and Fantrur 

The Action of Light Energy upon Vegetable Organisms. 

The necessity of plant life for light is greater than that of 
any other living organism. This is axiomatic. Without 
light energy plants become colorless, of imperfect structure 
and growth. In the absence of light it is impossible for 
them to take from the air the carbonic acid, absolutely indis- 
pensable to their existence. Nor can they by means of the 
chlorophyll assimilate it to their needs, setting free oxygen 
in the process, and retaining the carbon in new combinations, 
such as sugar, gum, starch, cellulose and albumen. 

A study of the action of light upon vegetable organisms 
is much less complicated than that upon animal organisms, 
by reason of the absence of the nervous system in the former. 

It is assumed by most physiologists that there is a direct 
chemical effect from light energy on the chlorophyll. This 
effect is dependent not only upon the intensity but upon the 
quality of light. All the frequencies of the spectrum have 
been shown to possess the property of producing chemical 
effects, although it is the higher and more refrangible rays as 
indigo, violet and ultra-violet which are regarded as es- 
pecially active. The chlorophyll function, that is the de- 
composition of carbonic acid, however, depends upon the 
longer and less refrangible frequencies of the spectrum, the 
red and yellow. 



It is clearly established b) the experiments • ens, 

rain and Bailey that I lie intense chemical energy of the 
ultra-violet frequencies is hadh home bj plant life. For 
each dass of plants a certain intensit) of light energ 

sarj i**r the mos! perfect performance of its assimilative 
processes; others again require hut little itj The 

latter are those plants wliicli are found u shady nooks, water 

courses, in dim forest aisles and in the depths of the ocean, 
ferns, mosses and marine algae, for example. Of die sun* 
loving - plants, the sunflower is a notable example, turning 
his face always sunward. 

Life of Hants in the Darl .—It has been proven by ihe 

experiments *<i Boussingault 1 that a plant destined to he 
green when kept in the dark consumes its reserves and loses 
weight; the life of a plant, coming Ot*t of the sea and kept 
trie, depends upon the amount, i.e., weight of nutri- 
tive matter contained in the a 

Necessity of Light for the Development of Chlorophyll. 
— It has been established by Tirniriaxeff 1 that the character- 
istic pallor of plants kepi in obscurity is due to the presence 
of protophvlliue or reduced chlorophyll. When they are 
transported to the light, the> become green through the 
absorption of the light energ) by the protophylline. 

There is another pigment existing in leaves, alongside <>f 
the chlorophyll, red in color, the erytrophyll of Bourgarel 
or Caroline of Arnaud, u b tf€ P de is very little known. The 
most vigorous leaves, which means those of the deepest 
greet], furnish the largest proportion of camtine: it is oh- 
served that it tends to disappear as does the chlorophyll 
when kept in darkness. 

Exceptions in the Wcessjty for Light in the Develop- 
ment of Chlorophyll —Chlorophyll appears in some plants 
budding in obscurity contrary to the general law. 

'Agronomic, V. 246^ 

omptes Rendus, \cad eta 5c I CIL, p 686, r 
■Cotaptti Reudua, Acad des Sc. C 751, 1885; C1I. iu> 
CIV. ]*)$, KS87; CIX gyi, 1889, 


Flahault 1 has shown that the bulbs of crocus vernus 
planted in the dark gives sprouts whose extremities are 

It has also been proved by Bouilhac 2 that the Nostoc 
punctiforme, develops a pale green tint in total darkness, 
if it finds at its disposition a hydrate of carbon, such as 

Grass when turned down continues to grow in the soil 
and presents a feeble green tint. This was noted by Kraus, 
but is a matter of common observation. 

A green alga has been found by a polar expedition at a 
depth of 2,000 metres in the Atlantic. Light penetrates into 
water but 200 metres, so that here is an organism taking on 
its green coloring. 3 

Flahault and Griffon 4 have by their experiments proved 
that the substance in the plants grown in darkness is really 
chlorophyll. Flahault examined an alcoholic solution spec- 
troscopically while Griffon caused some cotyledons of Pin- 
pignon to assimilate which had developed in darkness. Ex- 
ceptionally then it is seen that chlorophyll forms in the ab- 
sence of light a phenomenon at this time unexplainable. 

Chlorophyll Assimilation ; the Role of Light Energy in 
this Function. — The action of light in relation to chlorophyll 
assimilation has been thoroughly investigated independently 
of the respiration of plants. Among the modern l>otanists 
whom have studied the subject especially are Bonnier and 
Mangin. 5 They have shown that the two phenomena, i.e., 
respiration and chlorophyll function are distinct in their 
mode of action. Respiration, that is the absorption of oxygen 
and the exhalation of carbonic dioxide, goes on equally in 
light and darkness. I>y anesthetizing the plants under ob- 

'Ann. Soc Xat. Pmtan 6th St-rics t. IX p. 169. 

'Comptes Renting Acad. d. Sc. May 3. 1K98. 

'Lertddc and I'antrk-r. 

'L'Assiinilaiion ChlornphylHi'imr. Pan*. Xaiid. igoi. 

*Bonniirr and Mangin. 1/Action ('lilnpiphyllu-nne Scparrir nV la 
Respiration. Gmipt. Rend. Acad «1. Sc.. t. C. p 1303, 18K5 ct Ann. 
Sc. Natur. 7th Serif t III., p. 5, 



servatiun they have proved the independence of the two func- 
tions, and found tliat darkness does not influence respiration, 

but that absence of light suppresses the chlorophyll function. 

Chlorophyll production and function are dependent upon 
the presence of light But chlorophyll is no* the only sub- 
stance capable of fixing carbon under the influence of light. 
De CandoIIe 1 has showed that the red algae can disci r 
oxygen in the light ; while Engelmamr thinks that the dif- 
ferent coloring matters of the algae, phycoeyanine, pihy- 
coervthrine, and baeter io -jiurpurine of certain algae of the 
category of the Inutcriacccs, are also instances of assimilation 
carried on and dependent upon the influence <>r light en< 

At the base of all plant physiology is then this essential 
primordial phenomenon, or the assimilative phenomenon par 
lence of the plant, which consists of the decomposition 
of COm of tbe ambient medium and assimilation of carbon. 

This phenomenon is produced by the intermediary of a 
series of colored substances or chromophylls, of which 
chlorophyll is the most diffused. 

This assimilation of carbon is an essential exothermic re- 
action ; for its production, it is necessary that an external 
energy should be operative, and this energy is furnished in 
light. It is the absorption of light by the chloroleucites, or 
by the other colored substances analogous to chlorophyll, 
upon which the chlorophyll function depends* 

Nature of Chlorophyll Assimilation. — It is an established 
fact that under the influence of light energy a plant pro- 
vided only with water increases its weight of dry matter; i( 
fixes, in other words, its assimilative carbon. 

The author finds in this a counterpart of the acti-m of 
light energy upon the blood. In the latter instance it is a 
fixation or storing of oxygen, so necessary to animal life 

This exothermic reaction of chlorophyll assimilation pro- 
duced by light is believed 1 to be produced in the plant or- 

'Physiologic Vegetale, t I., p. 119. 
"Botanist-lie Z- ilung, 1883 


ganism simultaneously with the decomposition of CO., from 
the compensatory reactions which furnish the necessary 

The Effective Frequencies of Light Energy in Chloro- 
phyll Assimilation. — The decomposition of carbonic acid by 
chlorophyll is dependent upon the less refrangible rays, red 
and yellow. Plants and parts of plants grown in the dark 
have no chlorophyll ; the chlorophyll pigment being found in 
the light. From absence of light they become pale yellow 
in color, a condition known as ctiolatfon. 

The experiments of Siemens, Bailey and Deherain, to be 
referred to later on, showed that the electric arc gave a light 
needed for chlorophyll; but for that matter all artificial 
sources of light may take the place of sunlight so far as 
chlorophyll is concerned, for they all give out the yellow 
frequencies. It has been proven that sprouting plants will 
grow dark green in a light barely sufficient for the reading 
of large print. This shows that the quantity of light need 
not be large. 

By the utilization of various colored solutions, as filters, 
the different frequencies were cut off at will in the experi- 
ments made to determine the part of the spectrum necessary 
to the production of chlorophyll. For this purpose Pele- 
tier's bell jars were used. 

The chemical theory of the action of light energy on 
chlorophyll is the most widely accepted one. To it is op- 
posed that of Pringshcim. 1 The latter holds that the chloro- 
phyll pigment by the absorption of blue, violet and ultra-vio- 
let frequencies, without 1x.*ing decomposed itself, acts as a 
kind of light screen, lessening the degree of respiration, that 
is, the oxidation connected with the elimination of CO.., and 
increasing thereby proportionally the assimilative processes. 
especially as they pertain to the collection of carbon and the 
giving off of oxygen, within the plasma of the chlorophyll 




The subject of the frequencies of li^lit energy most 
favorable to chlorophyll development ha- tenstvely 

stigated by Gardner, Draper, Daubeny and Guillemtn, 
Guillemin used successive]] a spectrum obtained I 
different prisms, < 1 ) an ordinary prism, (2) a quartz prism, 
and (3) ■ rock-salt prism. In the first instance, all of the 
energy wive the ultra-violet was allowed to pass, in the 
second the ultra-violet, while in the third the infra-red were 
permitted to pas-. 

Later experiments b\ Ttmiriazeff places the maximum 
energy in the red region between the lines B and C In 
other words in thai part of die sp<vtnun absorbed by chloro- 
phyll. Always wherever in nature it occurs there is a con- 
stant proportion between tl bed and the work 

The Complementary Colors.— Engelmann has ad- 

v in -d the theory that it is always the frequencies comple- 
mentary to the color of the plant whose action is the 1 
pronounced. This is not confirmed by other physicists! and 
is especially denied b Em. 

The Action of Chemical Frequencies. — For the chloro- 
phyll function the energy of the chemical part of the spec- 
trum is necessary. Bonnier and ftlangin have found that 

this assimilation also takes place in the presence of ultra- 

violel energy. The amount of this assimilative energy has 
been measured by the O )._, decomposed. 

Experiments made upon the leaves of Araehidium and 
of maize give the following results: 


Bliuv Red. Great. 

cc cc cc 

Anirliidmin 0.054 0.03? 

Maize s 44° 0.R23 

There is then a co r respondence between the amount of 

energy and the intensity r t i the green coloration; conditions 
which are realized to the greatest extent from the effect of 
the blue frequencies. 


Just here the reader must be impressed with the simi- 
larity of effect upon the human organism. It is the blue 
frequencies of light energy even into the ultra-violet, which 
are absorbed by the blood, and there exists in the human 
being a distinct relation between the energy which he is 
capable of exerting and the intensity of the color of the red 

Influence of Light Energy upon the Growth of Plants — 
Actinauxism. — Dufour 1 from his experiments found that 
other conditions being equal, the plant growing in the light 
is more voluminous and more robust than that which has 
lived in semi-obscurity. Its leaves are more rich in stomata, 
its cells better walled, its grains of chlorophyll a great deal 
larger and more abundant and its assimilative energy much 
greater. This retardative action of light known as actin- 
auxism is profoundly beneficent to the plant. It is a matter 
of common observation that in the dark the stems of a plant 
elongate more than in the light. This increase in length is 
not due to the production of new cells but to an exaggerated 
increase of cells already formed. It is not a phenomenon of 
over activity but rather one of degeneration. In the pres- 
ence of light energy the growth is retarded, which is to the 
benefit of the plant, for there is thus secured the solidity, the 
equal partition of the chlorolcucitcs, which are absolutely 
essential to its life. Plants grown in darkness are so slender, 
so lacking in fiber, that they are unequal to the support of 
their branches. 

Plants grown in the dark have very long internodes and 
leaf-stems but practically no leaf surface. Through the 
effect of light in the assimilation of carbonic acid the growth 
of green leaf surfaces is accentuated. 

The Transformation of Light Energy into Electro-Mo- 
tive Energy. — Light energy is transformed in the plant by 
the changes of matter, and Waller 2 proved that light de- 

1 Influcncc de la Lumiere sur la Forme ct la Structure des 
Feuilles. Ann. Sc. Nat. hot. 7th Scric. t. V. p. 31 T, 1887. 
2 Compt. rend, dc la Soc. dc biolog. 1900, LII., p. 1903. 


relope an electro-motive energy in tlic assimilating: leaf more 
by the bright red frequencies especially those absorbed by 
the chlorophyll, than by the heat rays. 

Biedcrmann V researches show that certain plants, am> 
them iris, nicotine, begonia and nasturtium, are more 
favorable than others to demonstrate the existence of electric 
currents. If one of them be placet! in connection with a gal- 
vanometer by means of electrodes attached to leaves on 
different Bides, and one side of the plant be exposed io sun- 
light while the other side is kept shaded, then within from 
3 to JO seconds after exposure to sunlight there will be 
a flow of electricity from the lighted to the shaded parts 
amounting to .005 to .02 volt. This continues for about 5 
minutes, when the magnet begins to swing back and shows 
an opposite current of considerable magnitude. The mani- 
festations are similar to tin tani/ed nerves, The elec- 
tric current of green leaves is least in diffused daylight, 
greater in refracted light and most in direct sunlight. It 
is still further affected by the temperature, 20°C being the 
optimum for iris. The electric activity is destroyed by 
cooking the leaves nor are the electric manifestations found 
in plants that do not have green leaves, Biedcrmann con- 
cludes that this is proof that the g e neration of electro-motor 
force accompanies the decomposition of carbon dioxide of 
the air, the exhalation of oxygen, and the fixation of the 
carbon of the air, 

Influence of Light Energy upon the Movements of 
Plants. — In the transformation of energy which takes place 
in plants there may be distinguished two great groups of 
movements, viz., the movement of growth and the movement 
of irritation. 

Growth Movement, — Under the stimulus of light energy, 
plants present definite growth movements, which may be 
regarded as irritation phenomena. When certain parts of a 
growing plant with a definite periodicity move automati- 

f Dr. W. Riccfcrmann, Ergebnissc dcr Physiologic. 


cally one or more times, the phenomenon is known as nuta- 
tion. Of those periodic nutation movements made by the 
green leaves is that known as nyctitropic nutation. By this 
is understood the closing and the folding of leaves either up- 
wards or downwards against the common stem, according to 
the kind. It is the movement characteristic of sleep or rest. 
In the daytime the leaves are spread open that the light may 
fall upon them vertically. The sleep movement prevents the 
plant from too great radiation at night. These movements 
are due to the blue and violet frequencies. Red has the! same 
action as the absence of light. 

The growth movement is not dependent upon light under 
all circumstances. It is not required for the process of ger- 
mination, nor for the growth of the roots and many blossoms. 
It is necessary for the growth of many living parasites, Ijoth 
the endophytic, or those living in the IkkIv of plants, and 
endozooic, those living in the body of aninnls. 

In general light retards the growth under the conditions 
enumerated and this is also true of organisms above ground. 
By reason of this fact, the varying rate of growth at different 
times of day is explained. This rate is not for a time influ- 
enced by artificial exclusion of light. It i* in the morning 
that stems and leaves grow most actively and least in the 

The growth of plant- i- I'-s^w! by all the frequencies 
of the spectrum except the red and infra -red. a- will be seen 
from the effects of the eWtrir an- in the e/jjeri merits to \*- 
detailed under thit head. The nr/-* r'- frangible freq^enH'-s 
are the most injuriously ac'ive not or .; v ]*-.w. n ing the 
but destroying the orirani-rr: in par. 

Influence of IJ^ht Kr'T^y \:\s.n 
— Helictropism. — \\\ ?■.«•! : o*r'. 7. :-rr. i- 
development <: *:.': •-. - -">- f >. 
relation to the v r.r ft : '■: '."/■ * '■: '■-_';. 

It is a matter - : -'r.rr/.r. '/v-'Tv; : V'.r v ;:• " 
when left in a r"..zr. \v/r.\'A frn— *•«* *':*> ' 
toward the source oi lifch* 1* Ira 



• r .. r .. 

",T (m 



Plant i 

:r ' 



r\ ;• 

j s 


?.'*'! **a 




. W" 




•o :•■ 



Sachs 1 that in plants lighted from one ride only radial struc- 
ms and roots, bend until their Ion- :v parallel 

to the rays of light, and thai dorsiventral structun 
for example, assume a position in which their snrfacec 
perpendicular to the light rays. To those plants or or 
which turn toward the tight von Sachs applied the term posi- 
tively heliotropic, while those which turn from the light 
were termed negatively beliotropic lie formulated the 
three following laws, viz, : ( i ) The orientation of a plant 
toward or from the source of light is determined by the 
direction of the ray& [2) ( Mentation of plants is atf 
only by the more refrangible rays, blue and violet. (3) 
Light of constant intensity acts eouiinuoush as a 

Stems and leaf stalks are aa a rule positively heliotropic, 
while roots and rhizomes are almost all negatively hetio- 
tropic. Jn the former instance they gTOVt toward the li^ht 
source in the direction of the light rays, hut in the latter they 
turn away from the light source. 

To the entire phenomena, however, the term heliotrop stn 
is applied, A still farther modification of this heliotropic 
faculty i> observed ill the case of green leaves; the> turn 
themselves al right angles to the direction of light and are 
said to show a (ran-, verse or dia heliotropism If plants be 

moved from their normal position, their heliotropic move- 
ments take on curved movements, according to their rda 
to the source of light. Heliotropism is governed bj the 
degree of brightness of light. When the light is very bright, 
organs which are usually positive!) heliotropic may become 
ively heliotropic. This is an instinctive effort at 
self-preservation, for too much light is mimical to the 
normal development of the plant as well as too little. The 
direction of the incident light governs the heliotropic 

This phenomenon ha been extensivel} studied by \\ 1 

... n iiber Pflanzcn, Physiologic, Leipzig, 1887. 


ner, 1 Guillemin* and von Sachs. 1 They have found that the 
action begins with the frequencies of the green region and 
goes on up even into the ultra-violet, extending even beyond 
some radiations which impress salts of silver. The yellow 
frequencies are neutral, but on the other side the action is 
the same, rising on the side of the red but very feebly. 

Microscopically this heliotropism shows itself by intra- 
cellular displacements, by protoplasmic currents, by a true 
phototaxy of the grains of chlorophyll themselves which 
come and distribute themselves upon the irradiated surface. 

This heliotropic action was very prettily shown in 1890 
by George Romanes 4 in his demonstrations before the Brit- 
ish Physiological Society of experiments which he had made 
with fresh tender mustard plants. 

He sowed the seed in suitable small receptacles, and 
when it began to sprout placed them in a dark chamber. In 
this chamber electric sparks were produced by an induction 
coil at varying rates. Invariably the plants turned their tops 
in the direction of the sparks, even when these were produced 
so slowly as once a minute. It would seem as though every 
tiny plant were looking toward the source of light. The 
experiment is an interesting one. Whether the phenomenon 
produced was due to the presence of ultra-violet frequencies 
only, is conjectural. There is the electric action to be 
reckoned with and the ionization of the air produced by 
spark discharge. 

The Helianthus is a very striking example of this helio- 
tropic faculty. On a *unny day it orients its stem toward 
the east after the rising of the <un follows the sun even t<> the 
middle of the day. remains there immobile, until toward the 
end of the day it leans toward the west, resuming the vertical 
position during the night. 

'Die lieliotropischen Erscheinunjren in Pllaim-nrrichr. IVnk- 
schriften der k* Akad. dor Wi^en^cliaft. /u Wien. t. XL1II. i^So. 

a Ann des So. Xatur.. 4th Scrie. t. VII. p. 101. 1X57. 

3 Botani*che Zeitunp 1M5. 

*Ros\vell Park. A Report upon the Physic- and Therapeutic 
Value of Cathode and I'ltra violet Rays. The Medical \\\vs May 
30, 1903. 



L ocomo t o r Movements. — A study of plant life shows 
that many unprotected plasmic bodies, such as the swarm 
spore of many algae, present the phenomena of independent 
movement by means of their waving cilia. This movement 
is governed in part by temperature, and in part by the action 
of the incident light. These locomotor movements may be 
regarded as one of the irritation phenomena produced in 
plants by the stimulus of light energy. Microscopic inhabi- 
tants of the ocean, pond** and lakes, just as larger animals 
change their position by reason of the influence of light. 
Sunlight attracts them, and they often rise to the surface 
from the depth of the waters in which they live. The water 
changes in appearance, loses its transparency and takes on 
different colorings, dull green, bluish brown, or red when 
they are present in great numbers. Prominent afflORg the 
which will actually move themselves upon exposure to 
light, is a whole series of the lVsmidia, particularly the 
Clostcriuni monili ferum. 

Water plants, however, appear at the surface of the 
water; by reason of their production of oxygen, which les- 
sens their s|>eeifk gravity. Reproductive cells of the 
swarm spores, zoospores, which are capable of independent 
movement, as are the infusoria, move as far as possible in 
a straight line toward the source of light. This is a helio- 
troptc movement, hut some such cells are repelled rather 
than attracted by light, and are, therefore, regarded as nega- 
tively hcliotropie. Whether they turn on the longitudinal 
of their body or not, that is to right or left, again de- 
pends upon the light ray. 

Heliotropism is dependent, as are so many of the phe- 
nomena of phnt and animal life, upon the short and high 
frequencies of the blue region of the spectrum ; while the 
frequencies pi the red region, like darkness, do not affect 
their action at all. The creeping or aniftfaoid movements 
exhibited by the plasmodia of myxomycetes, as of "flowers 
of tan," are dependent upon the stimulus of light energy. 
These bodies move away from the bright spots into the 


shade, working themselves slowly along on their hase. They 
are, therefore, negatively heliotropic. The movements of 
chlorophyll bodies are possibly dependent on this plasma 
movement, and seems to bear a relation to the greater or 
lesser intensity of light. 

Every lover of nature is familiar with the intense deep 
green of the leaves of phanerogams, mosses and the pro- 
thallia of ferns. This is due to the slow changes in the posi- 
tion of the chlorophyll corpuscles in the protoplasm. Under 
the influence of the stimulus of light energy, especially the 
shorter and higher frequencies, these chlorophyll corpuscles 
collect mainly in the cell surfaces turned toward the leaf. 
While in the dark they collect mainly along the side walls of 
the cell, at right angles to the cell surface. Whether this 
is a direct influence of light upon the protoplasm, or an in- 
direct unfluence induced possibly by primary change in the 
chlorophyll corpuscles, is not certainly known. The posi- 
tion of the chlorophyll corpuscle varies during night and 
day. According to Stahl the position for the most part of 
flat chlorophyll corpuscles with regard to the incidence of 
light is divided into the "surface position" and the "profile 
position." The position of the chlorophyll corpuscle in all 
cases is governed by the following general rule : ( I ) When 
the stimulus of light energy is at a medium of brightness, 
the chlorophyll corpuscles turn so as to present the broadest 
surface possible. (2) When there is a maximum of light 
energy, i.e., direct sunlight, they turn their narrow edge to 
the light. (3) When there is a minimum of light energy, 
or darkness, the narrow edges are turned, as when the sun's 
direct rays fall upon them. 

In the second instance they present the edge of the leaf 
that the light energy may not be absorbed and act destruc- 
tively; while in the absence of light energy the change of 
position is that of rest or sleep. This movement is the prop- 
erty of the chlorophyll corpuscles or bodies in all assimilating 

They also change in form according to the degree of 



brightness. When the stimulus of the light energy is most 
favorable to their needs thej assume the flattest position, 
that is, a position horizontal to the superficies of the lenf. In 
common with the pigment cells of animal orga; lloro- 

phyll corpuscles .ire capable of contraction. This again is 

dependent UpOtJ the energy of the light stimulus. The gl 
of a plant may take mi a lighter or darker shade according 
to the degree of light energy. This characteristic of the 
chlorophyll corpuscles of plants finds its counterpart in the 
pigment cells of the chameleon. The protoplasmic current 
in plant cells, which frequently is only recognized under the 
microscope after mechanical stimulation, seems ordinaril} to 
he Independent of light, although it is proved to he governed 
by temperature and the presence of oxygen or contained 
water. The exclusion of light does not affect the protoplas- 
mic current li goes on just the same as far as is now known* 
rnal conditions, however, nro be so changed that the 
protoplasmic current may after all he radically influenced by 
light. Experiments were made by E. losing as folk 
i i i objects with frech flowing protoplasm were subjected to 
the effect of weak solutions of ether or chloroform, and (2) 
Mistitnent of the :iir necessary to their life, carbonic 
acid, was withdrawn by means of a suitable agent from the 
air. Under these conditions the protoplasmic current o 
to flow when the ligfll was excluded, hut resumed its course 
Upon its reaclmission. 

The injurious effects of electric arc light, which is, after 
nil. hut a miniature sun, were first noticed by Siemens m 
[88 1 as is shown in subsequent pages. 

Data as to the injurious effects of light on plant > vvas 
first furnished, by Pringshcim. There are no changes 
pecially characteristic of these injurious effects. The fol- 
lowing conditions have. howevi r. hern noted: rigidity, for- 
mation of nodes, concretions of plasma, granulation 
pecially in the cell nucleus, hut without any especial char- 

"Jahrl>. d Wissensch Botonik, igoi, Vol XXVI. 


acteristic. There is no such intense nor disruptive effect 
produced by light energy, when acting injuriously, as by 
heat. A sudden change of temperature intensifies corporeal 
movements. On the other hand, a maximum light intensity 
tends directly toward precipitation in the plasma and toward 
its rigidity. Contraction occurs only upon death superven- 
ing, but vacuolization does not take place. 

Influence of Light Energy upon the Plossom. — The color 
of flowers is influenced by the different frequencies. Pa- 
using various colored lights, various shades of the lilac, for 
example, may be obtained. The influence upon the aroma 
under the led frequencies is very great. Strawberries thus 
grown have a very delicious aroma and crassula flowers, 
which are nearly scentless in ordinary sunlight, give out a 
delicate banana-like fragrance. 

The absence of light retards the development of flowers, 
and their color is less intense in darkness than in sunlight. 
This diminution of intensity of coloring varies with the 
species, with some there is little change, but with oilier s a 
complete loss of coloring. As a rule, flowers thus developed 
are smaller, but on the other hand the peduncles are some- 
times more fully developed. They aho are less in size and 
weight, including the supporting pedicle*, save in those in- 
stances where the increase in the size «»f the peduncles coun- 
terbalances the diminution of the reM of the plant. 

Plant life in common with annual organisms is subjected 
not only to the chemical effect of light, but the thermal or 
heat effect as well. 

Following the introduction of electric light, tie influence 
of the latter in relation to phut life was studied. The fmt 
experiments were made by I lerve Mangnn in 1801. 1 P»y 
this experiment he showed that the electric light can cause 
the production of chlorophyll and also heliotmpism. or the 
phenomena of bending or turning to the light. 

In 1869 Prilieux J showed that the electric light, in coni- 

'Compte Rond. 5.3, jjx 
"Conipte Rfiid. '9. 410. 



mon willi other artificial lights, is capable of promoting as- 
similation, or the decomposition of carbon dioxide and water. 
General Pleasanton conceived the idea of growing vegetables 

and fruits in greenhouses constructed of blue and violet 
glass, and published his results in 1877, He reported the 

production of extremely fine fruit, and that the growth of 
figs was accelerated. xperimeots were next followed 

by those of C \Y\ Siemens in England ami I*. P. Deherain 
in France. 1 These were still further supplemented by the 
experiments at the Agricultural Station of Cornell Uni- 
versity in 1851 and 1 892." the latter comprising the only 
definite investigation of the subject upon what might be con- 
sidered a practical or horticultural scale. The English ex- 
periments, although eminently practical, were conducted 
by an electrician, the French were largely confined to phy- 
siological problems, while those of Cornell University 
were approached from the standpoint of the 

In Siemens* experiments, the lamp in the first instance 
was placed inside the greenhouse and in the second Bt»* 
pended over it. That is, in the first series, all the fre- 
quencies of the spectrum of an electric arc from the lowest 
to the highest were in evidence. In the second series the 
ultra-violet of less than 30 nncrocentimetres were cut off. 
In both eases marked effects upon vegetation in a verj short 
time were observed. 1 1 is light source measured photo- 
metrically produced K400 candle power. When the light 
placed inside of the house and no absorbing media for 
the ultra violet frequencies intervened plants within 3 
or 4 feet of the arc suffered much, the leaves of melons 
and cucumbers which were directly opposite the light, 
turned up at their edges and looked as though they bad been 
lied. In general, however, all plants which were ex- 
I to normal conditions during the day and to 6 hours 

'Quoted in Bulletin ]Q< Agricultural Experimental Station Cor- 
nell University. Aug., iH*/i 
'Bulletin 30 and jj 


of electric light at night, "far surpassed the others in dark- 
ness of green and vigorous appearance generally." 1 

The electric light fruits had an equally good flavor with 
the others. Supplementary experiments were made in the 
following winter 1 880-1881, with a lamp of 4,000 candle- 
power inside a greenhouse of 23.118 cubic feet capacity. 
The light was in operation all night and at first it was used 
without a globe. This again meant the exposure of all the 
plants to the short and high frequencies or ultra-violet rays. 
"The results were anything but satisfactory." A clear glass 
globe was then placed upon the lamp, following which most 
satisfactory results were obtained. Peas, raspberries, straw- 
berries, grapes, melons, and bananas fruited early and 
abundantly under continuous light ; solar light by day and 
electric light by night. The strawberries are said to have 
been "of excellent flavor," and the grapes of "stronger flavor 
than usual." Competent judges pronounced the bananas of 
"unsurpassed flavor," and the melons "remarkable for size 
and aromatic flavor." Wheat, barley and oats grew so 
rapidly that they fell to the ground of their own weight. 
The effect of interposing a mere sheet of thin glass between 
the plants and the source of electric light was most marked. 
On placing such a sheet of clear glass so as to intercept the 
rays of the electric light from a portion only of a plant — 
for instance, a tomato plant — the effect was most distinctly 
shown upon the leaves. The portion of the plant under the 
direct influence of the naked electric light, though a distance 
from it of 9 to 10 feet, was shrivelled, whereas, that por- 
tion under cover of the clear glass continued to show a 
healthy appearance, and this line of demarcation was dis- 
tinctly visible on individual leaves : not only the leaves, but 
the young stems of the plants soon showed signs of destruc- 
tion, when exposed to the naked electric light, and these 

Proceedings of the Royal Society, XXXI, 210 and *)3. Rep. 
British A. A. S. 1 88 1. 474- 

Abstracted in Nature, J0|^^5O, M arcfc j^j88o. Editorially 
treated in the same issu 


Lir.Hi i 

destructive influences were perceptible, though in a less 
marked degree, st a distance of ao Fed from the source 
of the light. 3 Here the significance of the intense chemical 

activity of the ultra-violet frequencies cannot fail to be 


In the other u jcperiments Siemens placed an 

electric lamp of 1400 candle-power about 7 feci above a 

sunken melon pit which vv is sacred with glass. Tlw 

was protected bj a dear glass globe. In these experiments 

the light euei filtered through the media of 2 thick* 

of glass, effectual!) absorbing all the ultra-violet fre- 
quencies, and plants of mustard, carrots, turnips, 
beans, cucumbers and melons were placed therein. ITw arc 
in Operation 6 hours each night, and the plants bad 
sunlight during the day. In all cases those 1 'hints "ex; 1 
to both sources oi light, showed a decided superiority in 
r over all the Others and the gre e n of the leaf was of a 
dark rich hue/ 1 HeHotropism was observed in the young 
mustard plants. Electric light appeared to be about half as 
effective as daylight. The condensed moisture in the r 
of the greenhouses at night obstructed the passage of the 
light. At one time the light was suspended over two parallel 
pits nearly 4 feel apart, and the effect was observed upon 
plants under the glass and in the uncovered space. In all 
cases the growth of the plants was hastened. Ffc >\venng was 
hastened in melons and other plants under the glass. Straw- 
berries which were just setting fruit were put in one of the 
pits and part of them were kept dark at night, while the 
others were exposed to light, The most of the berries bad 
attained to ripeness and presented a rich coloring after 
14 days, the light having burned 12 nights, while the 
fruits 00 those plants exposed to daylight only bad hardly 
begun to Show a Blgll I E ' 

Siemens also imtcd that the presence of the electric arc 
light enabled plants m the greenhouses to bear a higher 

'Siemens* Report. 


temperature than they otherwise could. While Siemens' 
observations and conclusions were applied by him to a prac- 
tical "electro-horticulture," as he termed it, yet they have 
a value from the physiological side as well. 

The following conclusions were reached by Siemens as a 
result of his observations : 

( 1 ) Electric light is efficacious in producing chlorophyll 
in the leaves of plants and producing growth. 

(2) An electric centre of light equal to 1.400 candle- 
power, 2 metres from growing plants, appeared to be equal 
in effect to average daylight in March. More economical 
effects are to be obtained by more powerful light centres. 

(3) That the carbonic acid and nitrogenous compounds 
generated in diminutive quantities in the electric arc exer- 
cise no sensible deleterious effects upon plants enclosed in 
the same space. 

(4) That plants do not appear to require a period of 
rest in the 24 hours, but make increased and vigor- 
ous progress if subjected during the daytime to sunlight 
and during the night to electric light. 

(5) That the radiation of heat from powerful electric 
arcs can be made available to counteract the effect of night 
frosts, and is likely to promote the setting and ripening of 
fruit in the open air. 

(6) That while under the influence of electric light, 
plants can sustain increased stove heat, without collapsing, a 
circumstance favorable to forcing by electric light. 

Deherain's experiments were conducted at the Exposition 
d'Electricite in Paris in 1889. A small conservatory stand- 
ing inside the exposition building was divided into two com- 
partments. One compartment was darkened and the glass 
painted white upon the inside ; this received the electric light 
and all solar light was excluded. The other compartment 
was not changed. A lamp of 2,000 candle-power was used. 
In such an exposition building sufficient sunlight is not re- 
ceived to maintain a healthy growth. The unprotected arc 
was used first and run continuously. Barley in head and 



flax in flower! also Chrysanthemum*, roses, pelargoniums and 
a variety of ornamental plants were brought into this com- 
partment. Most of tliem were seriously injured after ft 
days of continuous lighting, All the pelargoniums lost 

their leaves, canuas discolored, ioutm/ -clocks were tarnished 
and bamboos were blackened. "But the most curious I 
was produced upon the lilacs; all the parts of the leaves that 
had received the dir» I rayfl from the lamp were blackened, 
while those protected by the upper leaves preserved their 
beautiful green color, and the Impression produced upon the 
epidermis by the electric rays had the B photo 

graphic plate/* Azaleas, deutzias and chrysanthemums 

similarly affected. It was found that the discoloration 
did not extend beyond the first layer of the palisade cells. 
Those plants subjected t)0 solar light by day and the eleetrie 
arc by night were injured in the same manner, but not to the 
same degree. Old leaves suffered most. The pelargoniums 
sent out mere sh<»«ts, and the young leaves resisted the ac- 
tion of the light much longer than the mature ones* The 
flax continued to grow and the barley ripened, Plants 

i tit the electric light alone were able to assimilate, but 
the action was very slow. ( )ne hour of sunlight was equal 
to several days of electric light in assimilation. In two 
weeks the condition of the plants was so bad that the arc 

i hereafter protected by means of a glass globe. The 
experiments then proceeded in the same manner. Sprout- 
ing seeds grew alone in electric light for a time, then drooped 
and died, not being able to make true leaves, Sprouting 
maize turned black, but maize in full growth remained in 
good condition for two months, tin nigh not growing any 
more. While new leaves appeared on roses and other plants, 
they grew slowly or not at all. In previously formed fruits, 
seeds did not ripen, nor Sowers appear, save in the case ol 
barley, which made good Many plants remained sta- 

tionary, ami assimilation for all was much more feeble than 
with the unprotected arc. 

Deherain, in discussing the physiolog) of the plant under 


experiment, came to the following conclusion : ( i ) The 
electric light from arc lamps contains rays harmful to vege- 
tation. (2) The greatest part of the injurious rays are 
modified by glass. (3) The electric arc contains enough 
rays to maintain full-grown plants two and one-half months. 
(4) The light is too weak to enable sprouting seeds to pros- 
per or to bring adult plants to maturity. 1 

The experiments at Cornell conducted by Bailey ex- 
tended over a year, and were made more from the gardener'.- 
point of view than those of Siemens and Deherain. They 
are of equal interest with those detailed, but as they were 
made under conditions favorable to the growth and develop- 
ment of vegetation, and for the purpose of showing the value 
of the energy of the electric arc in forcing establishments, 
they are not so striking in their injurious effects. 

In the experiments of Siemens and Deherain, the action 
of the great quantity of the higher and more refrangible fre- 
quencies, the blue violet and ultra-violet present, produced 
in a very marked manner their characteristic effects. 

Conclusions from the Cornell University Experiments 

(1) That electric light may be used under such condi- 
tions as to make it fairly comparable to sunlight in its power 
to promote protoplasmic activity. 

(2) The electric light acts as a tonic to plants so that. 
they are able to endure adverse conditions which otherwise 
would cause them to collapse. 

(3) That the electric light is a true vital stimulus, since 
the effect of its use at night upon plants is essentially the 
same as that of the longer day of the arctics upon plants 
growing in that region. 

Nature 2 in commenting editorially upon Siemens' ex- 
periments and the relation of light to vegetation, said : "But 
the scientific interest of its present application must rest 

VAm. Agronom. VII. 551 (1S81). Quoted by Bailey. Agricul- 
tural Bulletin 30, Cornell University, Aug., 1891. 
^Nature, March 11, 1880. 

Li.. lit ENERGY. 

mainly on the fact thai tin cycle of the transformation of 
energy engaged in plant life is now complete, and that, start- 
ing from the energy stored up in vegetable Fuel, we can run 
through the changes from heat to electricity, and thence to 
light, which W€ now know, we can store up tn vegetable 
fuel again/* To-daj these experiments as well as tbos 
Deherain, Bailey and Cornell ruiversity serve to still fur- 
ther emphasize ilk- value "t" light energy from artificial 
SOtirces tor the purpose of treating disease. The author's 
interest in die subject of tight energj was originally greatly 

stimulated by the result of these experiments. 

Conclusion, — From all this mass icperimental data, 

the paramount importance of light energy upon the vegetable 

organism is evident. Vegetable life is not possible save in 
the presence of light Chlorophyll assimilation, the funda- 
mental phenomenon of plant life, is only possible in the pres- 
ence of ti v of light, The frequencies of the 
trum influencing this function are the red, orange and the 
violet Xor is the r<Me of light confined to this phenomenon 
of vegetable cellular life alone. It plays another most im- 
portant part in the life of the phm. In connection with 
geotropism, it rules the direction of the growth of the stem, 
the leaves, their position, the position of the flowers, in short; 
it determines some actual movements of the three parts of 
the plant. Tn the production of all these phenomena the 
chemical part of the spectrum is alone active. 

The Action of Light Energy upon Bacteria. 

Introduction. — In a study of the bactericidal power of 
light one cannot fail to detect great discrepancies at the 
hands of different experimenters. These are due to the 
conditions of experiment. In no instance, at least but sel- 
dom, and with solar energy not at all, is the light intensity 
measured. To be exact, the hour of the day, the nature of 
the place of experiment, the condition of the sky, clear or 
obstructed, the light intensity, the temperature and the in- 
fluence of the culture medium arc all factors in the results, 
and similarity of result will only follow when each and every 
experimenter takes into consideration all rf these factors. 
For practical work, it is sufficient to speak of the bactericidal 
power of the light, but not for laboratory experiment. 

The influence of these different factors is considered first, 
with the results obtained by the various experimenters taking 
them into account. In the subsequent pages the bacterici- 
dal power of light is discussed in its more practical relation, 
rather than in its laboratory relation. 

Transformation of Bacterial Species under the Influence 
of Light Energy. — Aside from the phototactic phenomena 
presented by bacteria there is also the phenomena of trans- 
formation of one species into another under xt 



of light energy, as was described in the case of the H yp ot ny * 
oetes by Elfving 1 and Laurent. 2 

Laurent experimented with the bacillus discovered by 

mil: in the waters of the city of Kiel. Light \>h 

considerable role in the development of the coloring matter 
i^i chromogenk bacteria, and on the other hand, according 

to the intensity, acts to suppress the chromogenie function, 
lie found the Kiel bacillus cultivated upon a potato, fcQ show 

ai the end of 24 hours a purple color. Prom exposing to the 
light a series of cultures for a varying time, Laurent estab- 
lished that at the end of 3 hours the bacillus was decolorized 
and modified to the forming of a new race, decolorized and 
stable. D'Arsonval and Charrin reached analogous conclu- 
sions from their experiments with pyocyanic bacilli. 

The Influence of Temperature— It has been observed hy 
Duehux 1 apropos of the Aspergillus Ni.^er and of the 
Bacillus Ramosus that hi the neighborhood of the critical 
temperature a difference of a half to a degree between the 
tWO cultures can produce profound differences between them. 

Influence of ibe Culture Medium. — This has been care- 
fully considered by Dnclaux. The bactericidal action of 
light is markedly influenced by the nature of the culture 

That experiments may have their full value a pre- 
method should be fallowed: a well-defined nncrobie species 
selected, an appropriate culture medium employed, and the 
time of exposure to the light energy exactly measured. 

Duclaux's experiments were made upon the spores of a 
bacillus of milk, the Tyrothrix Seaber. and upon a coccus 
found in the boil of Biskra I Biskra-Button — see Chapter 
XII.) 1 probably identical with the streptococcus pyogenes, 
and from them he reached the following conclusions : 

(1) The degree of resistance to the sun of the spores 


'Studien uber die Emwirknng cks Lictites atif die Pilze, 
■tngfofs, [890. 

'Annate dc rinst Pasteur, 1888. C R, Soc, Koyak Bot de 

Belgtqiie t. XXVIII, E|88 

Traitt de Microbiologic, t I. Paris, 1898, 


of various bacilli is variable with the genus of bacillus, and 
for the same bacillus, with the nature of the liquid in which 
it has been cultivated. 

(2) It is hardly more than at the end of a month of 
exposure that these spores, preserved dry in a balloon of 
glass, begin to become incapable of developing themselves in 
an appropriate medium. 

(3) The cocci, of which the spores are unknown, are 
more rapidly killed than the spores of the bacilli. 

(4) These cocci are less resistant insolated in the dry 
state than when they are contained in a culture liquid. 

(5) The death of all microbes is as much more rapid as 
the insolation is stronger, and a great deal more prompt even 
under a feeble sun than in the dark or in diffuse light. 

The minimum duration of resistance was in those ex- 
periments of 12 hours of insolation in July; the nnximum 
duration of 2 months, for some spores of bacilli insolated dry. 

At the same time Arloing 1 made analogous experiments 
upon a well-defined species, the bacillus anthrax, and made 
parallel observations upon variations of virulence and varia- 
tions of vitality produced by light. 

By these experiments he proved that gaslight sufficed to 
retard the evolution of enseminated spores, while sunlight 
transformed the cultures into a series of "vaccines" grad- 
ually attenuated. Arloing found that the spores were killed 
at the end of 2 hours of exposure in the month of July 
with a temperature of 35 C. ; while it was necessary to have 
30 hours of exposure to render sterile the mycelium of the 
same bacillus in full development. The spores show them- 
selves less resistant to the action of light than the bacilli 

Roux 2 also made a study of the action of light energy 
upon the anthrax bacillus, lie found that the vitality of the 
spores exposed to sunlight were preserved to the 29th hour 
at the minimum, while the maximum time was the 54th hour. 

"C R., 1885. t. C. p. 3/8. t. CI., i). 501. 
2 Annalcs de l'lnstitut Pasteur, 1.887, t. I., p. 445. 


After 83 hours of insolation there lated 

spores, sheltered from the air that gave some beautiful cul- 
tures. This is again illustrative of the fad thai the niicro- 
hieidal action "i light is dependent upon the presence of 

A> a result of many experiments RotlX concluded that, 
after 3 or 4 hours of . tm tasotated medium 

has undergone the chemical cl vhich renders it unfit 

for the development of the Spores which are lint \ el killed 
and will he only In the 30th or 4<nh hour. The modifi- 
cations brought about in the medium which are 80 profound 
as to prevent the generation of the spoT< S are not, however, 
sufficient to prevent the evolution of bacilli already formed, 
which are better ahle to withstand the light energy. If 
bouillon which has been insolated and will no longer permit 
charhon Spores to germinate, he sown with bacterium fila- 
menlosum. it wall multiply there in abundance. Whatever 
modifications the nutritive medium exposed to the action 
of light produce, the presence of oxygen is necessary. 

Upon exposing charbon spores to the action of the light, 
RottX found that those contained in open glass tubes with 
free access to the air became sterile; while those placed in 
closed tubes would germinate in the same bouillon after in- 
solation, if the containing mass were transferred into an 
aerated tube. 

The Role of Accessory Conditions in the Bactericidal 
Action of Light. — The influences which govern the bacteri- 
cidal action of light energy are (1) the medium, {2) the 
atmospheric condition, whether humid or dry, and (3) the 
influence of the air itself. 

A study of the influence of these conditions serves to 
elucidate the subject still further. 

Moment's 1 experiments demonstrated the influence Of 
the medium, lie exposed to the sunlight some piece 
blotting paper soaked with eharhon blood, and at the same 

'Anodes de riitstitul Pasteur, t. VI- 1892. 


time some of the same blood tij>on sterilized plates. By 
inoculation he proved that the char1>on bacterium was killed 
on the sterilized plates in 6J hours of insolation; while the 
pieces of blotting paper still gave some virulent cultures after 
16 hours. In the latter instance, the charbon bacteria were 
protected by the fibers of the paper. 

Momont has also experimented to determine the influence 
of the atmospheric states of humidity and dryness, but the 
point is not yet elucidated. 

The experiments of Pansini, made at Xaples. consisted 
in exposing tubes containing some sowings made upon 
gelatin or gelose. These tubes were closed with cotton 
wool and exposed to the solar energy. A tube was taken 
each half hour, and placed in the incubator to observe its 

Pansini concluded that the action of light at first simply 
retarded the growth, and subsequently proved destructive. 
The time required for a lethal effect upon the bacterial 
growths varied with the microbic species. 

He has made a very precise series of experiments which 
show the relation of the bactericidal action of light energy 
to the time element. Exposure to the sun was made of 
some pendant drop cultures of anthrax bacillus. The tem- 
perature varied between 32 and 40°. lie drew from one 
every 10 minutes to count the germs by the method of 

The second dav's examination is as follows : 

Plate exposed 10 minutes to sun 300 colonies 

20 " " " 130 " 

" 30 " " " 4 " 

" 40 " " " 3 " 

'* 50 " " " 4 " 

(x> " " " 5 " 

g£ '* 1 hntir 10 minute^ o 

11 '* to the same temperature in the dark. .J520 

The spores of the bacteria insolatol dry vveCMyucii inn re 
resistant, and gave a table of the folio wi] 

168 u.,ii] • 

Plate exposed 30 minutes to the light ;/■■ colonics. 

[ hour 208 

• ■•- - H H 4# 

3 30 

" 4 34 " 

I* H », it >• Q it 

a a T »* ... 

8 hours and more 

Plate exposed m the dark 1015 

By these tables it will be seen that a much more rapid 
destruction took place in the first moments of exposure, only, 

however, nie complete at the end of more than an 

hour fur the bacteria, and of more than 8 hours for the 


The Action of Insulated Frequencies of Light Km 
tip* iii Bacteria. — 1 KArsonval and Charrin, 1 studying the 
causes of exaltation, or of attenuation of the microbe and 
the media which they inhabit, analyzed, amongst others, the 
effects of light upon the bacillus pyocyanicum. Submit- 
ting this bacillus to the action of the white light, he found 
first a diminution of its chromogenic power, lie then ex- 
d Ihe "sown" tubes, for a time varying between 3 
and 6 hours, one in the chemical part, the others in the 
calorific part of the spectrum, all the other conditions being 
equal. Next a drop of each of these cultures was placed 
upon agar. After 2 days in the incubator ai 35 degrees, 

only the culture submitted to the red light gave pigment, 

die other remaining colorless. By increasing the time of 
exposure of the tuht-s to the light, those that received the 
violet light remained sterile while the others gave prosperous 
culture. These authors take care to note the excessive 
variety of the effects obtained according to the intensity of 
the luminous sources. 

Ledoux-LebanF studied the action of the luminous agent 
upon the diphtheria bacillus. He proved that the action Of 
diffuse Itgbt did not prevent the development of cultures of 

'Comptes rendus Acad, des Sc, jativ., 1804. 
'Arrliiv. dc Med F.xper. fit d'Anat pathol., 1803. 


bacteria, while the solar light sterilized the bouillons of cul- 
ture in a few clays; that diffuse light killed the dry cultures 
of diphtheria, spread in thin layers, in 24 hours of illu- 
mination, and had a bactericidal power for bacilli in dilu- 
tion in distilled water. He confirmed also the observation 
that the bacillus of diphtheria, like other microhic species, 
is killed by the most refrangible rays of the spectrum, the 
less refrangible rays having no bactericidal action. 

The action of both sunlight and that of the electric arc 
upon the growth, and the life of various kinds of micro- 
organisms, is then firmly established by extensive and very 
carefully conducted experiments, and that this action with- 
out the living tissue takes place can in no sense be gainsaid. 
That it takes place in living tissue by the action of the 
chemical rays which penetrate them, is disproved by the 
experiments of Bernard and Morgan. 

This bactericidal action of light was first pointed out by 
Downes and Blunt, 1 who in 1877 communicated a paper to 
the Society on the "Influence of Light upon Proto- 
plasm." They called attention to the fact, that diffused and 
still more direct sunlight had the power of killing putrefac- 
tion bacteria, that heat rays play no part in this action, and 
that the most active are the blue, violet and ultra-violet fre- 
quencies, but that the red and orange are not entirely in- 
active. Their experiments still further show that it did not 
matter whether the bacteria were damp or thoroughly dried, 
but that the presence of oxygen was of absolute necessity 
for this bactericidal effect. They were of the opinion that 
the action of light in these experiments upon bacteria was 
not to be sought in a modification of the nutritive basis, and 
also considered the possibility that ihc products of metabol- 
ism in the bacteria may be influenced by light. These facts 
were at first disputed by Tyndall, but they soon had abun- 
dant confirmation from all sides. The experiments of 
Dow f nes and Blunt were made with any bacterial mixture of 

1 Proceedings of the Royal Society of London, J}fC, 
Vol. XXVI.. p. 488. and Dec 


decomposing liquids conveniently at hand, but later inv 

>rs have used pure cultun 

In 1892 Marshall Ward 1 presented a paper to the Royal 
,\ of London, entitled "Experiments on the Action ol 
Li^ht on the Bacillus Anthracis." th 
light on bacilli from the Thames, and found that in all c 
solar and electric-arc spectra exerted no perceptible a 
whatever in the infra-red, red. gion, 

while nil the bacteria were injured <»r destroyed by the rays 
from the blue <>r violet spectrum. The intervention of a 
thin piece of glass resulted in cutting off a large proportion 
of the effective rnys. The most distill those 

at the end of the blue and beginning of the violet, were to 

SOtne extent effective, even after reflection from the inner 
face of a quart/: plate coveting the film, and the glass on 
which it was supported. Ward als.i showed that moulds and 
ere injured in their development and growth, a 
fact more recently corroborated by Bte. This former inves- 
tigator goes on to say that tl Its evidently sul 
that the naked arc light may prove tn be a very efii 
disinfecting agent for use in hospital wards, railway car- 
riages and Other places where the rays could be projected 
directly on the organisms. In this report Professor Ward 
staled : 

"The results are a> startling as they are important, for 

if the explanation given of the phenomena observed in the 

following experiments turns out to be the correct one, we 

stand face to face with the fact that by far the most potent 

: in the purification of air and rivers of bacteria is sun- 


Professor Ward in connection with Sir Oliver Lodge- 
exposed cull lire plates to the ultra-violet energy of the 
electric arc alone, as to the energy of other parts 

'Quoted from Committee Report on Lighl as a Diagnostic and 
Therapeutic Measure by Margarei ^ Cleaves, M.D., to American 
Electro-Therapeutic Association, Sept, 25, -? !k . sad 27, 1894. 

•Lectures i<< Medical Practitioners upon Physics, by Sir Oliver 

W. Lodge Archives Roentgen Ray. June. J 904. 


of the spectrum, establishing a much more powerful bacteri- 
cidal action with the ultra-violet alone. 

In the more recent investigations, care has been taken to 
consider not only the fact of the bactericidal action of light, 
but also the physical factors in that action. To that end the 
sources of light were taken into account, their intensity ami 
the use of light filters as well. These physical factors were 
most carefully considered in the experiments of Mcrnard and 
Morgan to be subsequently detailed. 

Theodore Geisler 1 in 1892 found no qualitative differ- 
ence between sunlight and electric light, only a quantitative 
difference. In the course of some experiments on the 
typhoid bacillus he found that the most decided effect 
was produced by the rays from the violet end of the spec- 

His experiments were conducted in the following man- 
ner: two cultures were sown with typhus bacilli and placed in 
the dark, two in the sunlight, and two placed 1 mm. from an 
electric arc of 1.000 candle-power. 

He concluded as follows : That there is no qualitative 
difference between the electric arc and solar light, and that 
all the frequencies of the solar and ihe electric arc spectrum. 
save the red, retard the development of the typhus bacillus, 
and that this influence is so much the stronger the more re- 
frangible are these frequencies, i.e., the shorter and higher 
their wave length. 

The author has substantiated this action <>f the chemical 
frequencies, visible and invisible, as obtained from a 7-am- 
pere water-cooled iron electrode lamp, a 5-minute appli- 
cation destroying them completely. The same was true of 
the staphylococcus pyogenes aureus. 

P. A. Khmelevsk) ,-' of St. Petersburg, after prolonged 
experiments, concluded that both solar and electric light 
have an undoubted inhibitory influence 011 the growth of 

'Centralblatt ftcr Bal 
2 Quotttl by author in 


Klebs-Ldfficr 1 discovered that diffused light does not 
prevent the development of cultures of diphtheria at ordi- 
nary temperatures, or at a temperature as high as 95 C F., 
but that sunlight arrests development, and after an exposure 
of several days sterilizes bouillon. This bactericidal power 
of light toward the bacillus of diphtheria is due almost ex- 
clusively to the rays of greatest refraction, those at the other 
end of the spectrum having little or no action of this kind. 

There is a very extensive bibliography upon this subject, 
and Freund 2 refers to the following experimenters: 
Faligati (i), Arloing (2), Duclaux (3), Lubbert (4), 
Janowski (5), Santori (6), Raspc (7), Geissler (8). Kol- 
liar (9), Dandrien (10), Chmiliewsky (11), Gaillard (12), 
Marshall Ward (13). Ledoux-Lebard (14), Pansini (15), 
d'Arsonval and Charrin (16), Roux (17), Billings and 
Pcekham (18), Kruse (19). Koch (20), P>eck and Schultz 
(21). Dieudonne (22), Buchner (23), v. Esmarch (24), 
Giunti (25), Martinaud (26), Moment (27), Wittlin (28), 
Richardson (29), Shickhardt (30). and Ruhemann (31). 
This bibliography is appended for the benefit of the reader 
who mav not have access to Freund's book. 

'Quoted by the author in 1894. Com. Report on Light as a 
Diagnostic and Therapeutic Measure Am. Electro-Therapeutic Ass., 

a Freund, Radiotherapy, Rebman & Co. 



(1) Compt. rend., 1879, Vol. LXXXIX., p. 959. 

(2) Ibid., Vol. C, p. 378, and Vol. CI., p. 511. 

(3) Ibid., 1885. 

(4) Ref. in Raum, Zeitschr. f. Hyg., Vol. VI. 

(5) Centralbl. f. Bakteriologie, Vol. VIII., p. 167. 

(6) Boll, della Accad. mcd. d'igiene, Roma, Vol. XVI., 
p. 386. 

(7) Einfluss des Sonnenlichtes auf Mikrobcn. Disser- 
tation, Schwerin, 1891. 

(8) Centralbl. f. Bakt., Vol. XL, p. 161. 

(9) Ibid., Vol. XII., p. 836. 

(10) Annales d'Hygiene, 1888, p. 448. 

(11) Wratsch, 1892, No. 20. 

(12) These de Lyon, p. 396. 

(13) Proceedings of the Royal Soc. of London, Vol. 
LII., p. 393, and Vol. LI1L, p. 2^. 

(14) Arch, de medec. exp., etc., Scr. 1, Vol. V., p. 779 

(15) Riv. d'igiene, 1889. 

(16) Arch, de physiologic norm, ct patholog., Vol. VI 

P- 335- 

(17) Ann. de Tinstit. Pasteur, 1887. 

(18) Centralbl. f. Bakt., Vol. XIX., p. 244. 

(19) Zeitschr. f. Hygiene, 1895, ^22. 

(20) Ueber baktcriologische Forschung, Berlin (Hirsch 
wald), 1890. 

(21) Zeitschr. f. Hygiene, Vol. XXIII. 

(22) Arbeiten aus dem Kaiserl. Gesundheitsamte, Vol 

(23) Centralbl. f. Bakt., Vol. XL, p. 781, Vol. XII., p. 
217, and Arch. f. Hygiene, Vol. XVII. 

(24) Zeitschr. f. Hygiene, Vol. XVI. 

(25) Stat. sper. agrar. ital., Vol. XVIII. 

(26) Compt. rend. Acad. d. Sc, Vol. CXIII. 

(27) Annales de Linstit. Pasteur. i8()2. 

(28) Wiener klin. Wochenschr.. 1896. 

(29) Transact, of the Cheni. Sue., 1893. 

(30) Friedreich's Blatter f. gericht. Mcd. 1893. p. 405. 

(31) Zeitschr. f. diat. und phys. Therapie, Vol. IV. 


lOfllg the lower forms of life, especially upon bad- 
strung li^lu has a fatal action. 

The bactericidal action of light belongs to the ultra-x ii 
end of th<* SpeCtfUIti. 

By means of an ordinary are lamp bacteria may be killed 
in from 5 t<> 8 hours, but by means oi rated 

arc light tlir- I quarts* the) can be 

killed in as many minutes 1 Ptna 

Both solar and the electric light, when diffused, arc much 
in when concentrated, and require much I 
to exert their bactericidal and disinfed OH, IT 

tion is very mild with an incandescent light as compared w ittl 
the electric arc and the sun, nor is it t<» be regarded 
germicidal agent, although :t is by no means inert, as it has 
abundant blue and violet frequencies, which are chemically 
active* Blue light oi shown by 

Kaiser to have a bactericidal action. See Chapter XI \ 

Below the ultra-violet then, the spectrum is live 

as a direct 1- but there is a modifying in- 

fluence exerted by the chemical frequencies 1 blue and violet) 

mg to a diminution of the virulence and ultimate death 
of patbog 

Dieudontte observed that direct sunlight will kill 1 
teria in one-half hour, diffused daylight in 6 hours, an 
electric arc light of 900 nominal candle-power in 8 hours, 
and an electric incandescent lamp in 11 hours. 1 The 
action of sunlight upon bacteria depends upon the season of 
the year, as its intensity naturally varies. The experiments 
of Fin sen. Bang and Strebel show that concentrated sun- 
light cheeked the growth of bacteria after one minute, and 
caused death in 5 to 7 minutes. Concentrated arc light 
checked the growth after 4 to 5 minutes and killed the 
bacteria in from 15 to 20. Arc lights with metal electrodes 
and the electric spark kill micro-organisms after a few 
onds, 5 to j<>- 

*Dieinlnnnt\ QUOted by Preunih 



The disinfectant action of light has been clearly demon- 
strated after the rays have \ enet rated clear water to a depth 
of at least 30 centimetres. This shows that water exposed 
to the sun's rays, for example, if perfectly clear and not of 
great depth, can be freed from pathogenic organisms. I>ut 
as it has been shown by Uernard and Morgan in their ex- 
periments, that 2.5 centimetres of water is sufficient to cut 
off four-fifths of the rays from the middle of the ultra-violet 
region, in which are the active bactericidal frequencies, it 
follows that this disinfectant action of solar light to ex- 
posed water to a depth of 30 centimetres must be due to 
a penetration of the visible chemical frequencies, blue anil 

The bactericidal effects of sunlight have been extensively 
studied. The evidence shows that sunlight plays an impor- 
tant part in nature in the disinfection or self-cleansing of 
rivers. 1 The water of rivers contaminated by sewage is found 
to become free from bacteria after having flowed for some 
distance. That a part of this demonstrated effect may be due 
to dilution, to deposit of sediment, and to absorption or 
decomposition of substances by plants or animals is very 
probable. Still the disinfection of running water is un- 
doubtedly contributed to very largely by the chemical fre- 
quencies of sunlight. It also has an effect upon the dust of 
streets. This was the subject of experiment by Wittlin,- 
who showed that it was disinfected in a high degree by sun- 
light. The bactericidal effect of direct sunlight upon germ- 
containing clothes, bedclothes, etc., was tested by von 
Esmarch. who found that the action is confined to the ex- 
terior layers of the objects, and docs not penetrate into the 
interior at all. 

Tubercle bacilli are quickly killed by direct exposure to 
the solar rays, the time varying according to circumstances, 
from a few minutes to several hours: while the diffuse rays 

Tratisnitz: Inrinenc^^H '^ Mnnirh -nr l'l ;ir. Munich, 

'Quoted I 


will destroy these organisms in from 5 to 7 days, their viru- 
lence diminishing tx -r death. (Koch.) 

The bactericidal effect of light is dependent (M5 the quan- 
tity of light. It appears to have been proven l>y K 
that an arc lamp using 5 amperes of current as m an ordi- 
nary electric- 1 ight bath, has practically mi power over the 
micro-organisms of the skin. In the case «>f arcs taking 
from 60 to 75 amperes, Frcund- found thai no bactericidal 
action took place when the rays v\ I through living 

tissue. The ear of a black rabbit was stretched bet w een 
the rays and a {date culture of staphylococcus pyogenetts 
aureus. The culture was placed in the incubator after an 
hour's expoaure, but the next day was found to be CO* 
with colonies of bacteria. The same negative result fol- 
lowed the experiment with the ear of a white rabbit, and 
also with the ear moistened with adrenalin. Tn all 3 cases 
the inflammation of the ear developed in 24 hours. 

B] a Sufficiently prolonged exposure to the active solar 
rays practically all pathogenic bacteria and sports may be 
destroyed. "The germicidal action seems to he <\ue par- 
tialis to changes in the medium involving its contained 
en, but chiefly to a direct action of the chemical fre- 
quencies of light" 

Different kinds of bacteria are differently affected, some 
being much more quickly affected than others. The experi- 
ments of Larsen 4 showed that the bacilli of typhus, diph- 
theria, plague and splenic fever have verv little resisting 
power, while tubercle bacilli and staphylococci offer greater 
resistance. Light is favorable to the growth of some forms. 
This was observed b\ Kngelmann in bacterium photOl 
cum, by Gaillard in yeast and mould fungi, and by Schenk 5 
in a coccus cultivated from the fee 

'Zeftschrift fur Dial, unci Pbysikaltschc Ther. 
'Freisnd, Radiotherapy. 

The linn 1 1 t'ninivU of Preventive Medicine Prize Essay, 
W. w.iv ne Bab 

'Mitthettungeti aus Finsen's Med Lichtinstitut, h. & 89. 
B Larseo J Engelmann, Gaillard, Schenk. quoted by Fretmd, 


The spores and the bacilli of splenic fever offer different 
powers of resistance also, as shown by Arloing, who suc- 
ceeded in killing the former in 2 hours' exposure to direct 
sun heat, while from 26 — 30 hours were needed for the 

A degree of illumination used may be insufficient for the 
complete checking of the development, yet may in some 
cases prove harmful to the formation of pigment. But in 
the case of other bacteria again, i.e., micrococcus ochroleu- 
cus, light is a necessary condition for this. 1 All of the ex- 
perimental work shows that by the exposure to light the 
development of the bacteria is not only checked, but also the 
virulence of the micro-organisms is lessened. 

For the purpose of proving in what part of the spectrum 
the bactericidal frequencies are to be found, science is most 
indebted to Vlademar Bie, Sophus Bang, Bernard and Mor- 
gan. The two former are known in connection with Fin- 
sen, being associated with him in his work. 

Bie's experiments were made with the bacillus prodigiosus 
and the light from a 35 ampere arc at 44 to 46 volts, giving 
about 600 candle-power. The light was concentrated by a 
Finsen apparatus, and fell vertically upon the culture. Ves- 
sels with piano-parallel glass walls enclosing a layer of fluid 
3 cm. in thickness were used as light filters. As absorbing 
media Bie used ( 1 ) a f resli 1 % sulphuric acid solution of 
quinin with a few drops of sulphuric acid, which allows the 
passage of all the rays but the ultra-violet; (2) a 5% solu- 
tion of chromate of potassium, letting through red to green 
inclusive; (3) a \\% solution of bichromate of potassium, 
letting through red to green inclusive; (4) a il% solution 
of bichromate of potassium, letting through red to yellow 
inclusive; (5) a 1-7% solution of fuchsin, letting through 
red alone. 

The light intensity was determined by comparing the 
degree of blackening of spots, produced by exposure of 
aristo paper to the light during definite periods of time. 


i 7 8 


Hie found as a result of these experiments that all the 
; th irs ol the visible spectrum, ami the invisihle chemical 
frequencies ur ultra-violet (the infra-red were nut ex- 
amined!, in an increasing ratio from red onward, checked 
bacterial development The action was found to increase 
with the ratio of refrangibility, hut was especially marked ni 
the blue, violet and ultra-violet frequencies. It WHS 
after prolonged illumination that a bactericidal action was 
obtained from tin- red, orange and green frequencies. It 
was not until an exposure of | | hours had been made with 
light that even the faintest perceptible retardation of growth 
was observed from the action of pure red light. 

The experiments of Sophus Bang were conducted with 
the greatest care. He took into account all the conditions 
t<> be noted with regard to light-action, the strength of Kgh1 
used, the distance of the object from the ray source, the kind 
of rays passing the filters and the amount passing through, 
the p er ce n ta ge <d* light penetrating through the bacteria 
(taking into account the absorption ami refraction of the 
light through the containing vessel and the culture medium). 

Everything was so arranged in making these experi- 
ments that the beam of light should meet with as few ob- 
stacles as possible on its way from the light source to the 
object. The reflecting planes were as few and as simple, 
and the absorption and refraction as slight as possible; an 
even temperature was maintained, and measures were 
adopted for varying the strength of the light according 1 
the gradation desired. In his experiments Bang used an 
apparatus in which the bacteria culture was spread out for 
examination in the thinnest possible layer, e.g., as a sus- 
pended drop on thin quartz plate. This quartz plate was 
used as the lid of a "moist chamber/* which, in turn, was 
fixed in a box filled with water of an even temperature, kept 
constantly flowing by a paddle wheel. The light was then 
admitted through a quartz window in the side of the box f 
and its intensity and direction of incidence exactly- 
mated. Under these conditions Bang reached the conclusion 



that under the influence of light at a distance of 28 cm. from 
a 35-ampere 50-volt electric arc, at an angle of 45 to the 
axis of the carbon, after a part of the heat rays had been 
kept back by a layer of water 25 mm. in thickness between 
quartz plates, and at a temperature of 30° C, a 3-hours 
prodigiosus broth culture in a pendant drop is sterilized in 
about one minute, a 10 to 15 hours culture in from 3 to 
S minutes. The light acts more quickly at 45 °C. than at 
30°C, sterilizing a 3 hours culture in about half a minute. 

The older the culture, therefore, the more resistant it is 
to the action of the light, and further with increase of tem- 
perature the bactericidal action from light increases. 1 

More recently two English physicists, Hernard and Mor- 
gan, at the suggestion of Dr. Allen Mac fay den have con- 
ducted a series of very careful experiments to determine 
(1) to what portion of the ultra-violet spectrum is the bac- 
tericidal action due, and (2) is it a primary or a secondary 
effect due to the reaction established in the tissues. 

This well-known action of the higher and shorter fre- 
quencies of light vibrations, or light without heat, to destroy 
micro-organisms without the body, is axiomatic. This 
point was first covered by the experiments and verified at 
every turn. That organisms inside of the living body were 
destructively acted upon by light vibrations was regarded as 
a matter of considerable doubt. Just here it may be well to 
note in passing that the bactericidal action attributed to 
radio-active substances, to the X ray, to high-frequency cur- 
rents or to other forms of electricity, unless in the polar 
action of the continuous current, anodal. by reason of its 
intense acidity and free oxygen, cannot in any instance be 
regarded as an immediate lethal effect upon the micro-organ- 
isms within the tissues, but rather as an inhibitory action, 
while the reaction established in the tissues through the local 
or general expenditure of one or the other forms of energy. 

'For detailed description of Hie's and Banc's experiments the 
author is indebted to the English translation of Freund's Radio- 
therapy, pp. 406. 407, 408. 



rentiers them an unfit habitation for living micro-organisms. 
It beco me s simply a question of the so nr i ya J of the fittx 

And more, there is an action upon the oxygenating power 
of the blood-stream which tends to a removal of the detritus 
h jading the vascular system, and at the same time the pr< 
nets of cell necrosis. That there is an effect upon the 
products of bacterial metabolism a red by I 

and Blunt seems very certain, tending to their removal, an 
effect of more importance even than the actual destruction 
of the bacilli. 

By their experiments Bernard and Morgan 1 found that 
light was powerless to destroy bacteria in those cases wheat 
its rays were made to pass through any organs ncc 

before impinging upon the bacteria, and even the thinnest 
film of agar served to protect the bacterial cultures. Much 
less can the bactericidal rays penetrate living or dead tissue 
under the ordinary conditions of experiment. This state- 
ment thev proved in the following manner: 

The Ughl bom an automatic arc lamp, that is. a lamp in 
which the carbons wet* kept at a suitable distance by means 
of a clock-work arrangement, was allowed to pass through 
a metal cvlinder through which water constantly circulated 
to eliminate heat, and which was dosed at each end with a 
disc of quartz. An agar plate was thickly inoculated with 
an active culture of bacillus ooli communis, and exposed to 
the light directly after inoculation, and then incubated for 
24 hours or longer at 3?°C. The light was only per- 
mitted to fall on a portion of the plate in order that the 
organisms should grow naturally on the other part, and 
thus JCTVe aa a control A current of 7 amperes was used 
at a distance of 10 cm. from the arc. 

| n 11 seconds the comparative number of surface 
colmms was greatly reduced, but those in the depths were 

a \ftcr an exposure of 2 hours and under the 

^c conditions, the deep colotiies were stil 

Hy J. E Bernard and 


..,,,,. |. )lV . K „i F«ctori ... Plwtoti 


Again a portion of the human skin, in one instance the cor- 
tical layer, in another the subcutaneous cellular tissue, was 
stretched over the quartz disc of the apparatus covering it 
entirely. An active culture of bacillus coli communis was 
then placed by means of a sterilized brush, ui>on an agar 
plate ; this in turn was placed so that the light from the arc 
fell directly upon it after passing through the cooling cham- 
ber and the human skin. After a 2 hours exposure no 
effect was produced on the bacilli, as on incubating the 
plate at 37°C. for 24 hours, the resulting growth was 
found to be equally vigorous over the entire surface of the 

The experiment was repeated both with a living and 
with a dead frog's foot, and with equally negative results. 
The light passing at the side of the frog's foot produced a 
destruction of almost all the surface bacilli, while those pro- 
tected by the semi-transparent webbing of the foot grew 
normally. (See Fig. 4.) The reason why all the colonies on 
the surface of the agar are not destroyed even where the 
undisturbed light falls upon them is still undetermined. It 
is perhaps possible that some few of the organisms during 
the process of inoculation have been introduced under the 
surface, and not being strictly superficial, are protected by 
an overlying absorbent film of agar. 

From these experiments they were led to the conclusion 
that the bactericidal rays being non-penetrative, the thera- 
peutic effect of light might possibly be due to the reaction 
produced in the tissues by the light rather than by the direct 
bactericidal action of the rays themselves. 

A series of experiments were then made to differentiate, 
if possible, between the frequencies which are bactcrcidal 
and the frequencies of vibration which excite a reaction in 
living tissue. In this at the time of their report they had 
only been partially successful. 

In order to discover the most active bactericidal rays, a 
continuous-current hand- fed arc was used, and the spectrum, 
as transmitted by a spectroscope with quartz lenses and 


prisms, was allowed to fall on superficially inoculated 
plates. A subsidiary fjuartz lens n\ itf-ineh focus 
to project the image of the arc on the slit of the 
Scope, thus obtaining the spectrum of carbon in the 
same manner as for photography, the superficially inocu- 
lated bacterial plate being used instead of a photographic 

It was found that the bactericidal effect was entirely 
confined to the ultra-violet portion* as shown ill Pi 
The line shown at V is where the ultimate edge of the visible 
violet fell, the red in the spectrum falling at the e xtre me 
edge of the plate. The bactericidal lines are seen to begin 
at 2.$ cm. from the edge of ttft ten 1 

from that point for 1.8 cm, into the ultra-violet. The photo- 
graph of the plate showed that the ultra-violet extended i . * 
cm. beyond this. No effect whatever was obtained with any 
other portion of the spectrum after 2 hours 1 exposure, and 
with the slit of the spectroscope open to an extent that would 
have been regarded as inadmissible in photography The 
active bactericidal radiations have thus been accurately de- 
termined and lie in that portion of the spectrum between A sa 
( wave lengths) 3*287 and 2,265, nr ni about the middle I 
of the ultra-violet region as seen in a photograph of the 
spectrum of carbon. Wither the extreme ultra-violet nor 
those nearest to the visible violet region appeared to be a 
The affected portion of the bactericidal plates correspt 1 
to a photograph taken of this portion ni" the spectrum, and it 
was possible to identify the nearly sterile hues on the plate 
With those known to exist in the ultra-violet spectrum of 


The conclusion is, therefore, reached that relatively the 
action of the other portions of the spectrum is negligible 
with the activity of this portion, although when using white 
light it is possible that there is a slight action extending 
over the whole spectrum. This conclusion affords, then. B 
physical basis for similarity of therapeutic effect from widely 
different adjustments of arc-light mechanisms, giving 

1 _ 

Fie 5 -Plate Showing effect of ultra-violet rays upofl growth of 
hirteria V ultimate cd K c Of Visible Violet rays, to the right of 

- 'i 


values in white light, but at the same time it substantiates 
the use of mechanisms arranged to give the maximum of the 
visible and invisible ultra-violet frequencies. 

A third series of experiments was then made to deter- 
mine which rays were active in exciting reaction on the part 
of the tissues. These, while suggestive, are not yet re- 
garded as conclusive. 

The shaved skin of a rabbit, anesthetized to secure abso- 
lute quiet, was subjected to the spectrum, with the same spec- 
troscopic arrangement as before, and no effect whatever was 
produced after an exposure of two and three-quarter hours, 
with a current of 25 amperes. Guinea-pigs, white rats, 
frogs, and even a human arm were similarly subjected to 
the same spectrum, but with absolutely no evidence of tissue 
reaction whatever. 

An additional experiment seemed to show that the rays 
exciting this reaction exist somewhere in the ultra-violet 
region. A rabbit shaven on both sides of its body was sub- 
jected to the action of the light 25 amperes of current) pass- 
ing through the water-circulating apparatus. Contact was 
made with the quartz disc on one side for 5 minutes. Then 
the other side was exposed in the same fashion, save that a 
sheet of glass was inserted between the water-cooling ap- 
paratus and the skin. The second exposure lasted an hour 
and was made with a current of 25 amperes. On the fol- 
lowing morning, on the side exposed to the rays through 
glass for an hour, absolutely no effect had been produced 
on the skin, while on the side exposed but 5 minutes 
through quartz, and without the intervention of glass there 
was a well-marked redness. 

This, the author has clearly substantiated in the thera- 
peutic uses of apparatus arranged with ( 1 ) glass plates or 
discs, (2) quartz discs, and. also in experiments made upon 
culture plates, the bactericidal effect being active with the 
quartz, absent with the glass. The well-known transparency 
of quartz to the extremely short and high frequencies, ultra- 
violet, and their loss or absorption upon the interposition of 



glass, accounts Cor tin* results obtained both experimentally 
and therapeutically. 

All rays of the spectrum, save the greater part of the 
ultra-violet, readily penetrate glass, and any effect obtained 
with apparatus containing tenses <>i globes of glass is evi- 
dently due to the feeble penetration of a few of the fre- 
quencies on the extreme edge of tile violet as it merges into 
the ultra-violet region. To obtain the maximum effect of 
ultra-violet frequencies when combined with blue-violet is 
to secure the maximum result in the treatment of such path- 
ologies as lupus vulgaris, as has been done by Finsen. 

It is then clearly proven that the frequencies which ex- 
cite tissue reaction are to be found in the ultra-violet re- 
gion, but it is not yet accurately determined in just what 
portion of the ultra-violet spectrum they are located, 

In view of the results obtained with the spectroscope OH 
bacteria culture plates Bernard ant! Morgan made experi- 
ments additionally with the spectra of various metals, such 
as iron, cadmium, silver and aluminum. The results agi 
entirely with those obtained from the carbon spectra, save 
that the bacterial action was intensified in proportion to the 
number and intensity of the lines or frequencies in the bac- 
tericidal region of the spectrum. From the number of the 
lines in the spectrum of iron it was concluded that an elec- 
trode composed entirely or partly of iron should be found 
more actively bactericidal than a carbon one. This proved 
to he the case. The form of electrode fonud to be must 
convenient in these experiments was that in which, in the 
case of the positive electrode, the soft carbon core wa- 
moved and in its place was substituted a mixture consisting 
of the particular metal it was desired to use, with sufficient 
carbon in the form of sugar to prevent the core from drop- 
ping out when in use The negative electrode was un- 
changed. The respective electrodes were then fitted into 
the arc lamp, and the bactericidal power tested on a hang- 
ing drop specimen of bacillus cob communis. The slide ON 
which the hanging drop cover slip was placed was i 


posed of quartz, in order that the ultra-violet frequencies 
might be intercepted as little as possible. The hanging' drop 
thus mounted was placed on the water-circulating apparatus, 
the light from the arc being projected from below upwards 
on to the hanging drop. In making these various electrodes 
in the arc lamp, it was found that the time required to de- 
stroy the bacilli, with, in each case, a current of 1 1 amperes, 
at a distance of 10 cm. from the arc varied as follows : 

Ordinary carbons .10 minutes. 

Carbons charged with silver 30 

Carbons " " iron 15 '* 

Carbons " " cadmium 15 

Carbons 4< " aluminum 25 " 

To ascertain whether the bacilli were killed or not the 
hanging drop was examined from time to time under the 
microscope. When all the motility had ceased, the cover 
slip with the hanging drop upon it was dropped into a tube 
of peptone beef broth. This tube was then incubated at a 
temperature of 37 C. for some days to see if any growth 

From the table above it will be seen that carbon elec- 
trodes charged with iron and cadmium have twice the bac- 
tericidal effect of ordinary carbons; and the cadmium car- 
bons seem to be preferable to the iron ones, as they burn 
more steadily in the arc lamp. There is a good deal <>f evi- 
dence pointing to a bactericidal power on the part of the 
blue and violet frequencies, almost equal to the ultra-violet. 
but these spectroscopic experiments, as well as the following. 
indicate that such is not the case. 

An ordinary glass slide was used, though the lighi from 
the arc was passed after having been cooled by transmission 
through a water-circulating apparatus. The electrodes 
used were charged with cadmium. Although the motilitv 
of the bacilli was stopped after an exposure of 55 
minutes, they were not killed even after an exposure of an 
hour and 20 minutes, that is. in a period five times (a 



little more than five times — 15 minutes against 80) longer 
than was necessary to kill the organism when the quartz 
slide was used. This shows that the visible ehemical 
frequencies, the blue, indigo* and violet, which readilv 
through tile glass are not bactericidal under these conditions, 
^r only slightly so. The L r l ass intercepted the ultra- viok-t 
frequencies, preventing. therefore, their bactericidal power 
Comparison was also made between the results obtained 
With the hanging drop* culture, as just described, and those 
obtained from superficially inoculated agar phtes, under the 
same conditions, and it was found that although half an 
hour was required to kill the bacillus colt communis in the 
hanging drop exposed to the light, the same result was ob- 
tained on an agar plate in 5 nn nines. ( Jr. in other words* 
si.\ times as long is required to destroy the bacilli when thej 
suspended in a fluid medium. 

This observation led to still another experiment, vi>;,, to 
determine what proportion of the bactericidal frequencies 
is absorbed by the thickness of water they have to traverse 
in tl circulating lamps employed therapeutically. 

To determine the influence of this factor the following 
experiment was made: The water-circulating apparatus, 
as already described, consisted of a short brass tube with an 
inlet and outlet for water, the ends being closed with a quart? 
disc. The distance between the quartz discs was 2.5 cm., 
and represented the depth of water to be traversed h 
light, An extended image of the are was projected <»u to an 
agar plate, which had been superficially inoculated with the 
colon bacillus. The arc image was obtained b. means of 
a pinhole in the metal plate interposed between the light 
source and the agar film. A projected image of the positive 
and negative poles and of the image of the arc resulted. 
They found* however, that under these conditions the loss 
of light was mi considerable thai a very long exposure be- 
came necessary, and, therefore, substituted for the pinhole a 
metal plate with a slit in it. The slit was less in width than 
the length of the arc itself, and was placed about 3 cm from 


the arc, with the direction of slit at right angles to the axis 
of the carbons. 

An image was thus obtained which was in reality made 
up of a number of superimposed images similar to those 
obtained with the pinhole arrangement. On the agar plate 
the image was seen as a central broad violet band, above 
which was the narrow white band of light projected from 
the negative carbon, and below the brighter white band pro- 
jected from the positive electrode. 

As heat might be a possible disturbing factor, the images 
from the electrodes were eliminated from the experiments, 
only the effects of the broad violet band from the arc itself 
being considered. 

Although they had no absorbing medium other than air 
between the arc and the agar plate, the light was almost free 
from heat rays, any possible rise of temperature being quite 
negligible. Inoculated plates were then exposed in the first 
instance without any heat-absorbing apparatus, and subse- 
quently with a water-circulating apparatus interposed be- 
tween the slit and the inoculated agar film. 

It was found that an exposure of 5 minutes without 
the water-circulating apparatus had a greater bactericidal 
effect at a point of incidence of the light than a 25 
minutes exposure with it. In other words, that the light 
on passing through 2.5 em. of water lost four-fifths of its 
bactericidal power. This result they had hardly anticipated 
in view of the researches of Hartley and others, in which 
water was shown to be but .slightly absorbent either to visi- 
ble or ultra-violet radiations. 

The loss of bactericidal power may, however, be attrib- 
uted to general rather than to selective absorption. The 
quartz may be regarded as negligible, as its transparency is 
well known, and they subsequently found that it transmits 
the bactericidal radiations practically without any loss of 
absorption. It would, therefore, appear that in photo thera- 
peutics the generally used water-cooling appliance might 
well be dispensed with if the 1' -nild tr \-i\ bv 


Other means, and assuming that the directly bactericidal rays 
arc the only essential ones, which at present is by no means 

The next experiment was to determine whether, when 
using the electric arc, the effect is in am way a function of 
any particular current. It was well known that the efficiency 
of an arc as a source of light increase- as the current is 
increased. The ratio of light production is approxiu 
as follows the standard in this case being an efficient type 
of nil lamp : 

7 amperes ♦ . 39 

10 75 

15 amperes 117 

jo H . . 160 

' '< hi exposing bacterial plates in the a! >nve in versed ratios 
ut found that the action was exactly proportionate to the 
light produced, a current 10 amperes having approximately 
double the bactericidal effects of a current 7 amperes and 
so on. This was tested carefully up to 2$ amperes with un- 
varying results, showing that the action is exactly propor- 
tionate to the light efficiency/' 

While the colon bacillus was used principally* Bernard 
and Morgan also employed the following organisms with 
similar results: bacillus prndigiosus, bacillus subtilis, micro- 
coccus tetragenus, staphylococcus aureus and bacillus tuber- 

These experiments conclusively establish that while 
quarts transmits the bactericidal frequencies without anv 
absorption, quartz used in connection with water-cooling 
apparatus is much less active, as a part of the active fre- 
quencies are absorbed by the water. The best therapeutic 
effect has been obtained by the author from using the 
c of light; (r) in general conditions all the radiant 
energies of the are. (2) in local lesions direct from the arc 
through a compressing lens of quartz only, without the in- 
tervention of water. 

\ that the frequencies which excite tissue reaction are 
so exactly located in the spectrum and thi bactericidal n 
LS definitely known, it will be possible to have light median- 


isms so arranged as to give the maximum effect. Then h 
will be a question of administering the active principle of 
light energy, with the precision of drug therapy. 

This work of Bernard and Morgan, although substan- 
tiating the work of Finsen and many other observers, is the 
first to definitely locate the active bactericidal frequencies. 
It will go far toward placing the therapeutic use of light 
energy on an absolutely scientific basis, as against its some- 
what empirical use as still practised to-day. Clinical work 
points also with unerring fidelity to the need of a source of 
light energy rich in chemical frequencies, ultra-violet es- 
pecially, where it is desired to excite tissue reaction by a 
localized application. 

The question of bactericidal action is not the paramount 
one, but it is the ability of the same frequencies ( ultra- 
violet) to excite intense tissue reaction upon which thera- 
peutic results depend. 

The frequencies of the red and green regions of the 
spectrum are neutral, and some observers have appeared to 
find them favorable to the growth of bacteria. All the evi- 
dence, however, places the bactericidal activity at the end 
of the spectrum most intensely chemical in its action, viz., 
the more refrangible blue, violet and ultra-violet frequencies, 
while the most recent and only spectroscopic experiment* 
exactly locate them in the middle third of the ultra-violet 

Sensitization of Bacteria. — As the gelatin bromide plates 
grasp the waves of short and high frequency with which 
space is filled by the millions and hold their energy fast, in 
particles of silver, so recent investigators 1 have endeavored 
to utilize the energy of longer and slower wave lengths 
green, yellow, and even red. by rendering the tissues sen- 
sitive with suitable substances just as is the bromide plate. 

All accumulated evidence shows that the bactericidal fre- 

'Schlesische GodUchaft fur vatorlandiselu* Kultur by PmlY>sor 
Neisser and Dr. Halberstadter. Section iA Medicine. Deutsebo Mrdi 
cinische Woeben>chrift. Fob. 18, 1904. Reviewed by Stepbano Leduc, 
Archives d'electricite. 



ijuencies aurl those exciting tissue reaction, i.e., blue, rtold 
ami ultra-violet, of the mosl refrangible of the spectrum, 
k least penetrative power, while the less refrangible 
frequencies, green, yellow and red, have the greatest pene- 
trative power. 

The question arose in the mind of Dreyer. 1 of Copen- 
hagen, as to whether living tissue does n-.r comport Itself 
as does a photographic plate, and if the same substances 
used for the latter will not act upon the former and render 

them sensitive bo the green, yellow and red frequencies 

the spectrum. 

Hie following experiments were made by Dreyer: cul- 
tures of prodigiosan, and also of die infusoria nassulo were 
placed in a small quartz chamber, cooled 1»\ a circulation 6f 
r, the liquid was sensitized by a t/5000 solution of 
erythrosin. which by itself is without any action upon 
infusoria or bacteria. The con c entr a t e d light of a 30 
ampere arc at JO volts pressure through a quartz filter was 
utilized. To study the action of the different frequencies of 
the spectrum, he filtered the light successively through glass, 
solution of sulphate of nickel, of eliminate of potassium, and 
of bichromate of potassium* The results are contained m 
the following table': 

a acting 

ifter which art? (lead 








Quartz . . . 

truin including 

the ultra-violet . 




a . . , . 

The visible 

tram . . • . 





Sulphate • 1 i 

Red, orange, yel- 

nickel, : 

low, jjreen and 





to 1 


Red, orange, yel- 



low, and ; 



than 4 


Bichromate ol 

Red, orange, yel- 



low . . . . . 

1 10 


than 9 


'Mittetlungen aus FinsciVs Med. Lkhfinstitut — [904, Heft VII. 


The action of the less refrangible frequencies of the 
spectrum upon sensitized infusoria and bacteria is very strik- 
ingly shown by the results of Dreyer's experiments, 

A 30-minute exposure of a culture of prodigiosus to 
the quartz spectrum of a lamp 26 amperes the non-sensitized 
bacteria were only killed in the ultra-violet ; while in the cul- 
tures sensitized by eryth rosin death is produced by the 
orange and yellow frequencies also. These have been 
rendered equally active with the ultra-violet by reason of the 
erythrosin solution in which the cultures were placed, and 
which has served to store the energy of the orange and 
yellow frequencies. In the doing of this a chemical action 
takes place just as with the silver of the bromide plate in 
photography, an action which is disastrous to the integrity 
of the micro-organisms. Drover found that the animal tis- 
sues were also capable of being rendered sensitive to the 
action of the orange and yellow frequencies. This he estab- 
lished experimentally upon tadpoles, rabbits, and upon the 
human skin. With concentrated light acting through 1.25 
mm. of skin Dreycr was able to kill in 32 seconds sensitized 
infusoria; but when non-sensitized under the same condi- 
tions death only ensued after fio minutes. 

Sensitized bacteria treated in the same manner died after 
20 minutes, while the non-sensitized were still alive after 1 1 

Thus it is shown experimentally that both bacteria and 
the tissues can by being covered with suitable media be 
rendered as sensitive to the longer, slower, less refrangible 
and more penetrating frequencies as tliev are to the very 
little penetrating frequencies of the ultra-violet. This action, 
according to Leduc. 1 does not in any sense depend upon 
fluorescence; for there are sensitizing substances which are 
not fluorescent, and fluorescent substances which are not 

There are, for example, fluorescent substances which 




absorb energy erf radiation at the same degree of erythrosin, 
but they are nut sensitizing — i.e., they absorb the eneru 
the more refrangible frequencies, but do not emit them at a 

r or less refrangible decree of radiation. On the 
n\ir\ they fix ur store the energy. This means work done— 
just as surely as the impression made upon the photographic 
plate by the silver bromide, nor is there any formats 
ti'xie material by the action of tight upon the sensitized 
liquids. If such a liquid is exposed to the light first and the 
infusoria or bacteria placed therein* no lethal action follows. 

The experiments reported by Dr. Halbcrstadter confirm 
at every point the researches of l)reyer t not only Upon the 
sensitized infusoria and bacteria but upon living tissue as 
well. The direct physical action of the bactericidal or ultra- 
violet frequencies upon bacteria is due to their short lengths 
and high frequency, i.e., the inconceivable rates at which 
they swing to and fro in their own free paths of oscillation. 
In so doing they have the power to agitate little things which 
appear in their path, such as molecules. By the profound 
agitation to which the bacteria are subjected by these fre- 
quencies, the death of the germ is assumed to result. It seems 
ver> probable that by this agitation they are worried very 
much in the same fashion as the small animal, mouse or rat; 
18 when shaken to death by a dog or cat. This physical 
tation in turn gives rise to a chemical process which insures 
the death of the bacteria. 

Mechanical Agitation Destructive to Germs. — Mechani- 
cal agitation of germs is destructive to them. The Lancet 1 
cites an instance where bacterial cultures were allowed to 
stand in the engine room of a large manufactory where there 
were incessant vibrations from the strokes of the engine. 
After four days the germs were destroyed and did not 
appear when the water was set in a quiet place. It is re- 
ported that Dr. S. J. Meltzer* has demonstrated that inces- 
sant vibrations of the stroke of an engine and violent shocks 

l Lotidoci Luieei, Fch. lQDJ. 
The Sttti. Feb. 14. 1904- 


are destructive of germ life. He found that the number of 
germs in the agitated fluid in no instance amounted to as 
much as one-tenth of those in the unshaken samples. It was 
also observed that the restriction in production increased 
with the duration of the treatment and that when the treat- 
ment was applied for a sufficient length of time the liquid 
could be freed from bacilli. The complete annihilation of the 
germs was accomplished in 10 hours of agitation, when 
sterilized glass beads were added to the culture. 

Different organisms were found to have different degrees 
of resistance, so that it was possible to eliminate them suc- 
cessively from a solution by regulating the shaking process. 
The cells thus split up did not form any visible debris, but 
resolved themselves into a fine powder, which offered no dis- 
tinguishing features under the microscope. Because of this 
it was concluded that there was in no sense a mechanical 
disruption of the cell, but that the effect was due to a chemi- 
cal action. 

From the physical point of view, the energy of oscillating 
light corpuscles is given up in the non-thermal mechanical 
agitation to the molecules, and this in partly atomic agita- 
tion or chemical change and the rest in heat or vibrations of 
the molecule; now if the molecular structure of the bacilli is 
unduly agitated by the swing of the oscillating light corpus- 
cles, the ultra-violet frequencies, the energy given up to them 
must be of such a nature as to result in atomic agitation or 
chemical change which involves the giving up of their con- 
tained oxygen, so necessary to continued vitality. 

In the living tissue while a direct lethal effect cannot be 
produced upon them by reason of their environment tin- 
atomic agitation would undoubtedly interfere with their 
vitality, and by reason of a chemical change. Tt would seem 
from experimental data and clinical observation that the 
same frequencies of light energy which unduly agitate bacUli. 
act as a physiological stimulus to the red blood corpuscles. 
increasing their oxygen-carrying capacity and therefore the 
oxidative processes of the entire organism. A certain vibra- 


ur.iiT eni:r«.v. 

tioiial activity is necessary to life, still another to the mainte- 
nance of health, while a third or greater degree is destructive 
of life, For example, in the phenomenon of heat we have a 
Vibrational activity — a tTJOde Of motion, and yet 'a few de- 
grees change in tempera ture either way will end the evanes- 
cent, fleeting, unstable and feeble thing or entity — life which 
was the last to appear in ihe midst of the stupendous cosmic 

war of matter and energy, and will l>e the first to vanish/' 1 
And the concentrated vibrational activity of die ultra-violet 
end nf the spectrum, while home in therapeutic doses by the 
higher organism, is fatal to the life of the lower. 

This destructive action of light energy upon mk 
lisms is assumed to be ( i ) on the plasma of the bacteria 
directly and (2) at die same lime to be indirectly injurious 
to the nutritive basis* by producing a photo-chemical change. 
Tn other words there h:is been expended an energy, capable 
of establishing chemical change, which influences not only 
the nutritive basis, but also normal physiological action, all 

of which tends to the rendering of bacterial toxins inert and 
the removal of the detritus. 

It was observed by Kruse 3 that by subjecting sterile 
nutritive bases to light, complex chemical bodies (peptones) 
were formed which checked develo p m en t . 

Richardson 1 proved that in fresh urine under the influ- 
ence of direct illumination, peroxide of hydrogen is formed. 
which is decomposed by die bacteria, the latter being killed 
by the liberated oxygen. Dieudonne showed that through 
the chemical action of light upon water, peroxide of hydro- 
gen is formed, most freely in the upper layers. As is well 
known, this compound is strongly antiseptic. 

Bactericidal action is very largely diminished under ex- 
posure to light when oxygen is excluded, as evidenced by the 
experiments of Dieudonne, Tizsoni and Cattant. 3 

'Lark in : Radiant Fncrgy. 
'Fremiti Radiotbi ■ 

"Arch- I Exper. Pathologic mid Pharmakologie, Vol. XXVIII , 
p 54. also Freund. 


The explanation of this lies in the fact that peroxide of 
hydrogen cannot be formed under these conditions. 

The most important factor in the human organism 
the author believes is to be found in the effect of the light 
energy upon the nutritive bases of Itactericidal growths 
pari passu with its physiological action upon the entire 
blood stream. This action is characterized by an increase 
in the amount of oxygen, which experimental data shows 
to be so prejudicial to the well being of micro-organ- 

Outside of the living organism there is a direct injury 
to the protoplasm. Dried spores from all nutritive material. 
as both Ward and Kruse have shown, are killed by sun- 

The movement of bacteria is also influenced by the action 
of light as well as their development and growth, both of 
which are checked. 

Winogradsky 1 and Beijerinck 2 found that sulphur bac- 
teria and the chromogenic bacteria always collect at the 
lightest spot, and they are thus positively phototaxic. This 
action is considered more at length under the action of light 
energy upon the elementary forms of light. 

It is not only a generally accepted fact tint light lessens 
the receptivity of an organism to living bacteria and to 
bacterial poisons, but the subject has been investigated ex- 
perimentally demonstrating its truth by Kondratjen. ( ieb- 
hard and Jousset. 

Baeder, 3 who investigated this point with great care, 
considered it an open question. 

Summary. — (1) Light energy is then not only a bac- 
tericidal agent of considerable power, but (2) the action is 
due to the more intensely chemical frequencies blue, indigo, 
violet and ultra-violet; while ($) there is no bacterial species 
which can resist the power of light if the light be intense 

*Zur Morphologic und Physiologic <kr Schwi-fcIbaktiTH-n. 
Quoted bv Freund. 

'Centralblatt f. Bakteriologic. Vol. XIV.. p. S44- (JuoU'd by 

'Quoted by Freund. 


enough, sufficiently concentrated and exposed for a sufficient 
length of time. 

From the chemical point of view the bactericidal power 
of light energy is a phenomenon of oxidation. For its suc- 
cessful action the presence of oxygen is necessary. 

The Production of Light by Micro-( )rganisms. — It is a 
matter of common knowledge that certain organic sub- 
stances, meat and fish, for example, especially salt-water fish, 
when the process of decomposition is first established, give 
off a more or less phosphorescent light, which is naturally 
most plainly visible in the dark. 

Pfliiger 1 was the first to observe that this peculiar phe- 
nomenon was an expression of the activity of micro-organ- 
isms. Since then Ludwig, 2 Fischer, 3 Beijernick. 4 Katz, 5 
Giard," and others have made pure cultures, and described a 
great number of photogenic bacteria. In this connection 
Fischer pointed out that even the ignis fatuus is to be ex- 
plained as a bacterial phenomenon. 7 

The intensity of the light given out by the different bac- 
teria varies greatly : the color also may differ, being white, 
bluish or greenish. Fischer found upon spectroscopic ex- 
amination, in the case of one bacterial species, a continuous 
spectrum from the D-line to slightly beyond the G-line with a 
maximum intensity between G and F. The strength and 
extent of the ignis fatuus in tropical waters is a matter of 
common observation and description. The phosphorescence 
of micro-organisms may be so great as to permit of telling 
the time of day; while photographs of cultures have been 
taken by the light produced by themselves. 

1 Piliiger's Archives f. d. Gcsamte Physiologic, Btl. X.. s. 275 und 
Bd. XI., s. 222. 

2 Zeitschr. f. Mikroskopie. I. 

"Zeitschr. f. Hygiene u. Infektionskiankh., II. Centralblatt f. 
Bakteriologie, III. 

*Ref. in Koch's Jahresher. 1890. s. 180. 

"'Centralblatt fii: Bakteriologie, IX. 

"kef. in Centralblatt f. Bakteriologie, VI. 

'These lights can, however, also be produced by other photo- 
genic organisms, for example, b> Peridinia. 


Bacterial Lamps. — In this connection it cannot fail to in- 
terest the reader to quote from MolischV communication to 
the Vienna Academy of Sciences in reference to the photo- 
graphic and illuminating power of micro-organisms in which 
he said he had been able to photograph phosphorescent cul- 
tures of bacteria after an exposure of 5 minutes, by their 
own light. In order to photograph other objects by means 
of this bacterial light, he constructed a special bacterial lamp. 
This consists of a large flask, whose interior is lined with 
salt-peptone-gelatin, previously inoculated with bacteria. 
On the second day following the inoculation the lamps begin 
to glow with a beautiful bluish-green light, due to the phos- 
phorescent colonies growing within. These living lamps 
have the property of shining with undiminished intensity for 
two or three weeks, and then gradually diminishing in 
strength. Their light is sufficient to permit one to recog- 
nize the face of a person standing two yards away, to tell 
the time, to read a thermometer, or even large-size print. 
In view of the freedom from danger of such a cold light, 
its use in mining operations or in powder magazines may 
become of importance. Organic light, particularly the rays 
emanating from glowing insects, such as the so-called glow- 
worm, has been made the subject of many investigations, 
and it was even asserted that this light has the properties 
of the Roentgen rays. Molisch, however, proved this view 
to be erroneous, as bacterial light acts just like ordinary 

The Free Access of Oxygen Necessary for the Phos- 
phorescence of Bacteria. — Of first importance among the 
necessary conditions for bacterial phosphorescence is the free 
access of oxygen. If the culture be in a solid medium only 
the upper layers are illuminated while a iluid medium on the 
contrary by shaking with air may be made luminous through- 
out its whole extent. 

The N. Y. Sun, March 15, I'Xtf. and the International Mod. 
Magazine, Oct., 1903. 


enough, sufficiently concentrated and exposed for a sufficient 
length of time. 

From the chemical point of view the bactericidal power 
of light energy is a phenomenon of oxidation. For its suc- 
cessful action the presence of oxygen is necessary. 

The Production of Light by Micro-Organisms. — It is a 
matter of common knowledge that certain organic sub- 
stances, meat and fish, for example, especially salt- water fish, 
when the process of decomposition is first established, give 
off a more or less phosphorescent light, which is naturally 
most plainly visible in the dark. 

Pfliiger 1 was the first to observe that this peculiar phe- 
nomenon was an expression of the activity of micro-organ- 
isms. Since then Ludwig, 2 Fischer, 8 Beijernick, 4 Katz, 5 
Giard, 6 and others have made pure cultures, and described a 
great number of photogenic bacteria. In this connection 
Fischer pointed out that even the ignis fatuus is to be ex- 
plained as a bacterial phenomenon. 7 

The intensity of the light given out by the different bac- 
teria varies greatly: the color also may differ, being white, 
bluish or greenish. Fischer found uj)on spectroscopic ex- 
amination, in the case of one bacterial species, a continuous 
spectrum from the D-line to slightly beyond the G-line with a 
maximum intensity between G and F. The strength and 
extent of the ignis fatuus in tropical waters is a matter of 
common observation and description. The phosphorescence 
of micro-organisms may be so great as to permit of telling 
the time of day; while photographs of cultures have been 
taken by the light produced by themselves. 

l Ptluger's Archives f. d. Gcsamtc Physiologic, Bd. X., s. 275 und 

Bd. XI.. S. 222. 

2 Zeitschr. f. Mikroskopie, I. 

3 Zcitschr. f. Hygiene u. Infektionskiankh.. II. Centralblatt f. 
Bakteriologie. III. 

'Ref. in Koch's Jahrcsher. 1890, s. 180. 

"Centralblatt fii: Bakteriologie, IX. 

"Rcf. in Centralblatt f. Bakteriologie. VI. 

'These lights can, however, also he produced by other photo- 
genic organisms, for example. b> Peridinia. 


T^acterial Lamps. — In this connection it cannot fail to in- 
terest the reader to quote from MolischV communication to 
the Vienna Academy of Sciences in reference to the photo- 
graphic and illuminating power of micro-organism^ in which 
he said he had been able to photograph phosphorescent cul- 
tures of bacteria after an exposure of 5 minutes, by their 
own light. In order to photograph other objects by means 
of this bacterial light, he constructed a special bacterial lamp. 
This consists of a large flask, whose interior is line.l with 
salt-peptone-gelatin, previously inoculated with bacteria. 
On the second day following the inoculation the lamps begin 
to glow with a beautiful bluish-green light, due to the phos- 
phorescent colonies growing within. These living lamps 
have the property of shining with undiminished intensity for 
two or three weeks, and then gradually diminishing in 
strength. Their light is sufficient to permit one to recog- 
nize the face of a person standing two yards away, to tell 
the time, to read a thermometer, or even large-size print. 
In view of the freedom from danger of such a cold light, 
its use in mining operations or in powder nnga/ines may 
become of importance. Organic light, particularly the rays 
emanating from glowing insects, such as the so-called glow- 
worm, has been made the subject of many investigations. 
and it was even asserted that this light has the properties 
of the Roentgen rays. Molisch. however, proved this view 
to be erroneous, as bacterial light acts just like ordinarv 

The Free Access of Oxygen Necessary for the Phos- 
phorescence of Hacteria.— Of first importance among Un- 
necessary conditions for bacterial phosphorescence is the free 
access of oxygen. If the culture be in a solid medium only 
the upper layers are illuminated while a thud medium on the 
contrary by shaking with air may be made luminous through- 
out its whole extent. 

The N. Y. Sun. Mnrrh 15. I'XV?. :m<l tin* International M«-'<1. 
Magazine, Oct.. icjoj. 


Ll<;il I ENERGY. 

enough, sufficiently concentrated and exposed for a sufficient 
length of tune. 

Ituiii the chemical point of view the bactericidal power 
of light energy is a phenomenon of oxidation. Foj 
oessfn] action the presence of oxygen is necessary. 

The Production of Light by Micros Nganiama. — It is a 
matter of common knowledge that certain organic sub- 
stances, meat and fish, for example, especially salt-water fish. 
when the process ui decomposition is first established, 
off a more or less phosphorescent light, which is naturally 
most plainly visible in the dark. 

Pfliger 1 was the first to observe that this peculiar phe- 
nomenon was an expression of the activity of micro-organ- 
isms. Since then Lttdwig", 1 Fischer,* 1 Ueijerniek, 4 Katz, & 
Giard. and others have made pure cultures, and described a 
great number of photogenic bacteria. In this coratectiosi 
Fischer pointed out that even the ignis fatuus is to be eat- 
plained as a bacterial phenomenon. 7 

The intensity of the light given out by the different 1> 
teria varies greatly: the color also may differ, being white, 
bluish or greenish. Fischer found upon spectroscopic ex- 
amination, in i c of one bacterial species, a continuous 
spectrum from the P line to slight!) beyond the ti-line with a 
maximum intensity between G and F. The strength and 
extent of the ignis fatuus in tropical waters is a matter of 
common observation and description. The phosphorescence 
of micro-organisms may he so greal as to permit of telling 
the time of day; while photographs of cultures have been 
taken by the light produced by themsdw 

l f*fliiger'a Archives f d, Gesamte Physiologic, Bd, X , s. 275 und 
Bd. Xi 

1 icbr. f. Mikrofkopie, I. 

"Zcitachr. f. Hygiene n. [nfefctionski&nkh*. 1!. Central Watt f. 
Bakteriologie, III. 

'Hi f in Koch's [ahresber. 1890, &, 1K0. 
• ntraJblatl in: Bakti rioJogie, IX. 

"Rcf, in Centralblatl f. Bakteriologie, VI. 

T The» can, however, also be produced by other photo- 

genic organisms, for example, b) Perktinia 


Bacterial Lamps. — In this connection it cannot fail to in- 
terest the reader to quote from MolischV communication to 
the Vienna Academy of Sciences in reference to the photo- 
graphic and illuminating power of micro-organisms in which 
he said he had been able to photograph phosphorescent cul- 
tures of bacteria after an exposure of 5 minutes, by their 
own light. In order to photograph other objects by means 
of this bacterial light, he constructed a special bacterial lamp. 
This consists of a large flask, whose interior is line 1 with 
salt-peptone-gelatin, previously inoculated with bacteria. 
<_>n the second day following the in»vulati»»n the lamps Ivgin 
to glow with a beautiful bluish-green light, due to the phos- 
phorescent colonies growing within. These living: lamps 
have the property of shining with undiminished intensity for 
two or three weeks, and then gradually diminishing in 
strength. Their light is sufficient t»» permit "tie to r\ % « ag- 
nize the face of a person standing tw-» \ards away, to tell 
the time, to read a thermometer, or even large-<i/e print. 
In view of the freedom from danger «>f ^uch a cold light, 
its use in mining operation* or in p'-wder magazines may 
become of imj>ortancc. < >rganic light, particularly the rays 
emanating from glowing in>ccts. such as die so-called glow- 
worm, has been made the subject «»t many investigations. 
and it was even assorted that this light has the properties 
of the Roentgen rays. Molisch. however, proved this view 
to be erroneous, as bacterial light act> iu>t like ordinary 

The Free Access of < >xygon Necessary for the Phos- 
phorescence of ttactcria— ■( >f rir>t importance among the 
necessary conditions for bacterial phosphorescence is the tree 
access of oxygon. If the culture be in a solid medium only 
the upper layers are illuminated while a iiui.1 medium on the 
contrary by shaking with air may be made luminous through- 
out its whole extent. 

The N*. Y. Sv.n. Marvh 15. hjo.i ;u\<\ the Med. 
Magazine, Oct.. mjo.v 



The Influence of Temperature in the Phosphorescence of 
< ria. — This phosphorescence is influenced by the sur- 
rounding temperature. If very high or very low the At* 
eence is prevented, even though the bacteria continue to live. 
Tlie limits within which they live are wide, but dependent 
amongst other things upon the temperature. 

Forster 1 found that a pure culture of a salt-water bacte- 
rium retained its power of light production and reproduc- 
tion at 0°. ToOhatisen- succeeded in reducing a culture of 
photogenic bacteria to — 12° without the complete cessation 
of pbospfa 'i > -< < nee. 

The Xecessity for the Presence «>f XaCl to Insure Phos- 
phorescence <>i" Bacteria,— It has been shown by various ex- 
perimenters, that all the light-giving bacteria require quite 
a high percentage of N'aCl in the culture medium in order 
to be able to produce light. The water of the sea is, there- 
fore, particularly suitable for the preparation of the different 

Two theories have been adduced with regard to the light 
production of bacteria : 

T. The production of light is a direct function of living 
protoplasm, and, therefore, just as inseparable from it as 
heat product it m. 

2. The living cell produces and gives off a substance 
(photogen), which outside the cell is luminous, 

Dubois 3 claims to have found such a photogen even in 
crystalline form, ant! Ludwig 1 asserts that, in e of 

the micrococcus pfluegcri, it is not the colonies themselves 
bin die products of metabolism, which give otT light. All 
other researches with regard to photogen have led to nega- 
tive results, and the theory mentioned under 2 can, there- 
fore, not be considered as proven, 

In general it may be said that light has no effect upon 

'CentralR i Bakteriologie, lb s, 337* 

Dtersuchungcu fiber Bakt phosphorescent Fischer, Diss. 
Wurzburg, 1 889, 

*Compte> Rendu s tie rAcademic des Sciences, Bil. t'\ II , - 502. 
*Centralbl f Bakteriotogie, Bd. tl. t i* 40. 


the phosphorescing power of bacteria, only Dubois 1 men 
tions a diminution in light production in bacteria that have 
been exposed to light for several days. The fact that the 
ignis fatuus can take on such extreme forms in the tropics. 
even when the sky is cloudless for days, would indicate that 
at least one form of light-pro* hieing bacteria [possesses a com- 
paratively great resistance to sunlight. A study of the ac- 
tion of concentrated electric light on these forms would Ik? 

The Action of Light on Vaccine, on Bacteria. Toxins, 
Enzymes, etc. — Finsen and Dreyer 2 have exj>ermientallv 
shown that light, and especially the ultra-violet rays, can 
weaken or destroy smallpox vaccine. The vaccine was 
placed in drops on plates of rock crystal and exjmsed to 
concentrated light from an electric arc light of 25 amperes. 
50 volts; the action of the heat was hindered by sprinkling 
with cold water, and the results were found by vaccinating 
children with it thereafter. An exposure to light lasting 
more than 10 seconds showed plainly a loss of strength in 
the vaccine, while an exposure of about 200 seconds was 
required to render the vaccine incapable of producing pus- 
tules. A prodigiosus culture was devitalized by the same 
illumination inside of 40 seconds. With illumination through 
blue or clear glass, which kept back the ultra-violet rays, the 
destruction of the vaccine was accomplished only after 15-20 

On the toxins of bacteria and all enzymes, which so far 
have been examined in this respect, light exerts a very de- 
structive action. 

Tizzoni and Cattanr found that long-continued action 
of sunlight not only is able to destroy the tetanus bacillus, 
but also to render inert the tetanus toxins. This destruc- 
tion took place most rapidly, when there was access to the 
oxygen of the air. These experiments were verified by those 

'Loc. cit. 

*Mitteilungon aus Finsen's Mod. Lichtinstitut. nxM. Heft 111. 

'Archives f. Kxpcr. Pathologic. iKgo. XXVI I. 

of Fcrmis and Cdlis, 1 according to which the tetanus poison 
completely bses its to ion after exposure to sunlight 

ibi Several days. Later experiments showed a similar eon- 
duct with regard to the toxins of other bacteria. 

With regard to enzymes, Dow ties and I Hunt. 2 who also 
Included this subject in their extensive and admirable re- 
hes, found that invert in was destroyed in sunlight, BO 
that it lost ils power to convert cane sugar. 

< rreen' has shown by unusually delicate experiments the 
destructive action of light on the diastalie enzymes occurring 
in the loaves of plants. This action is derived from the 
ultra-violet rays, while the blue, and especially the red rays, 
possess a favorable action, in so far as they arc able to con- 
vert the zymogen of the diastase into an active form, 

Schmidt-Nielsen 4 undertook lately in the above-men- 
tioned laboratory a series of experiments with regard bo the 
action of light on chymosin (rennet). He exposed it to 
light in small chambers whose walls consisted of quartz, and 
used as a standard of measurement (for the action of the 
light) the time required by 0-1 cm. :t enzyme solution to 
coagulate 10 cm/ 1 milk at a temperature of 37°. Non-con- 
centrated electric light and sunlight had very little influence 
OH the chymosin, while a very short exposure to concen- 
trated electric light lengthened the coagulation time quite 
materially. The action was ascribed to the ultra-violet 
rays, and the insertion of a piece of clear glass was suffi- 
cient to prevent this action. When the chymosin, after il- 
lumination, was kept in the dark an after effect was plainly 
ed after one daw 

An attempt to make the enzyme sensitive to the rays 
which can li seen, by the addition of a sensitizer (erythro- 
sin) gave negative results. As above mentioned, however, 

"Rcf. in CentraM f Bakteri XIL. No. 18, 

'Proceedings of Use K ndon, Vol XXVIH. 

'Philosophical Transactions of Ihc Royal Society of London 

Vol (IXXXVML & in- ioq. 

'Mttteilungen aus I Lkfetinstitutj 1904, Heft IX. 


Tappeiner 1 showed that enzymes as well as toxins can be 
sensitized 2 by the use of eosin and magdala red. 

On the chymosinogen — the zymogen or proenzyme of 
chymosin — the ultra-violet waves exerted a deleterious ac- 
tion similar to that on rennet, and contrary to Green's above- 
mentioned experiment Schmidt- Nielsen found that the red 
rays did not possess any active influence. Ordinary blood 
serum has the power of preventing the activity of enzymes, 
the active substance here — antichymosin — is also weakened 
by the action of light. 

The Action of Light Energy upon Hygiene and Sanita- 
tion. — From this array of evidence a practical deduction is 
to be made, viz., the influence of light in hygiene and sanita- 
tion. It is a perfectly well-known fact but not one that is 
lived up to even by the profession. The author would recall 
the experiment of Momont with the blotting paper saturated 
with charbon blood, the experiment of von Esmarch as to 
the extent of the action of light energy in destroying micro- 
organisms contained in bedclothing, of the purification of 
water by light energy, of the action of the electric arc upon 
noxious odors, to emphasize the need of the energy of light 
to keep our houses and hospitals pure. Disease will not 
breed in houses flooded with sunlight and air. The action 
of the sunlight is to destroy millions of morbific germs daily, 
not only in the air and on the surface of the soil but also in 
the water of streams. The latter has been shown by the 
experiments of Buchner, Praunitz 3 and Procaccini. 4 

The habit of keeping the window shades down, a very 
common practice even in the absence of direct sun glare on 
the window, is in direct opposition to fundamental physio- 
logical principles. Sunlight is not only purifying to our 
atmospheric environment, in its destructive action upon 
micro-organisms, thereby preventing disease, but it has a 

'Berichte d. d. Chem. Gesellschaft. 1003. Bd. XXXVI., s. 3035. 
*Sce Sensitization, Chapter XX. 

'Influence des ognuts de Munich sur I'lsar. Munich, 188c;. 
'Influence de la luniiere solaire sur les eaux d'egouts. Annald 
de Tlnstitut d'Igainc sperimentale, t. III.. 1893. 



still more deep anil intimate human relation of a sanitary 
nature, for an abundance of light energy la a necessary condi- 
tion of mental and bodily well-being. The recognition of its 
tonic psychical power is universal; the practical application 
not always made. In all properly organized peoples there is 
a love of light, and a fear of darkness is not confined to 
children. The sense of powerlessness, danger and alarm 
which the latter induces is shown by adults as well. Light 
energy is essential for all the purposes of life, for the supply 
<d" oxygen upon which existence depends. It is a universal 
stimulus. When it falls upon the eye there are established 
functional activities in the brain which are associated with 
intellectual and emotional states. That the blue frequencies 
exercise a depressing effect and the red an exciting effect 
upon the In a in seems well established : bttl in this connection 
it is neither the one nor the other which is considered but a 
complex of all the frequencies', heaven's own mixture the 
white light, that envelops us with its all-pervading energy, 
which is the normal psychical atmosphere. Variations in its 
intensity have in all probability widely different constitu- 
tional effects. But although the quality and intensity of light 
energy demanded by the individual living organism may 
vary, the need for it and dependence upon it is imperative 
for all. 

The influence of solar light as a disinfectant is chiefly 
upon the surface of translucent or opaque bodies. Any 
medium which cuts ,,h" the chemical frequencies from the 
blue into the ultra-violet region, as glass, dust and fog, as 
well as a clouded atmosphere, prevents this disinfectant 
process, so necessary to perfect hygiene and sanitation. 
Consecutive days of rain, mist and fog give an opportunity 
for the growth and development of pathogenic organisms. 
They usually are followed hy epidemics more or less severe 
of the diseases dependent upon the activity of these germs. 

Houses that are closed for several months in the year 
should he left with the shades all up and curtains looped 
back, in order that the sunlight may penetrate every noolfc 


and corner. In this way the growth of germs inimical to 
health will be prevented. And not only when they are 
closed but when occupied they should be flooded with sun- 
light. For this reason, heavy curtains which obstruct the 
ingress of the sun's rays are pernicious in the extreme. 
They not only exclude the light, but they readily become 
saturated, so to speak, with germ-laden particles of dust, and 
it remains only for the occupants of the house to become a 
little worn, tired, anaemic, from over care and anxiety, or in 
women from an exhausting menstrual flow, for these germs 
to find a fit lodging within the tissues and to actively 

By the action of those frequencies which penetrate and 
are absorbed, physically, there is established a synchronous 
vibration with oxygen molecules, which results in an impar- 
tation of energy and an increased oxidative power. 

Thus the chemical activities of light serve in hvgiene. 
sanitation, and also in disease : In the one instance to main- 
tain health, in the other to disinfect or destroy pathogenic 
organisms, and in the latter to check the inroads of disease 
by increasing not only the red blood supply but the white 
as well and the functional activity of the entire organism. 


The Action of Light Energy upon the Higher Organisms. 

Introduction. — There is in animals as in plants a stimu- 
lating influence on the functions of tissue elements and 
organs by the action of light. The impartation of energy to 
the living organism is transferred into a stimulus by which 
all the vital processes are quickened and heightened. There 
is produced by this stimulus of light either a direct influence 
upon the irradiated protoplasmic cells, or there is brought 
about indirectly, through the sense organs and nerves, cer- 
tain functions on the part of given organs. 

The Influence of Light upon the Development of Ani- 
mals and Man. — The development of many animals is de- 
pendent on light and without it development proceeds slowly 
or is suspended altogether. It was observed by William 
Edwards 1 that frog spawn in an opaque glass died, while 
spawn in a transparent glass became duly developed. 

Tadpoles develop more slowly in the dark than in the 
light. Schnetzler's 2 experiments prove that white light is 
more favorable to such development than green. 

The degree of development of animal organisms is influ- 
enced differently by the different frequencies of the spec- 

l De 1'influcncc des agents physique sur la vie. Paris, T824. 
"Archives des Sc. Physiques et Naturelles, 1874, Vol. LI. 


It was observed by E. Yung 1 that violet light helped 
on the development of the embryo of rana, salmo, and 
lymema, which was hindered or disturbed by other parts of 
•the spectrum or by darkness. 

Beclard 2 observed that flies' eggs develop more quickly 
under blue and violet glass than under red, yellow, green 
or white. 

Guarinoni n from his experiments believes that violet light 
acts more favorably on silkworms; while Goodnew noticed 
that maggots are much more quickly developed in pieces 
of meat exposed to the light than in meat kept in the dark. 
In his study on the activity of light on polypi Loeb found 
that the growth is not especially influenced by all the rays, 
but that only the more refrangible, that is, the blue rays, 
promote growth. The same effect on the other hand is pro- 
duced by red in darkness. 

Recently Leredde and Pautrier 4 have made a study of the 
development of animals under the influence of the energy of 
different parts of the spectrum. As subjects of experiment, 
tadpoles of the common rana temporaria were used. The 
solar spectrum divided into two parts was used ; the one 
comprising all the energy from the green, blue, indigo and 
violet, and the other the energy from the red. Two aqua- 
riums were constructed, one of photographer's red glass, col- 
. ored with proto-oxide of copper, and the other of blue glass 
colored in cobalt blue. Each was covered with a glass of 
the same color as the aquarium, leaving just space enough 
for oxygen renewal. Examined spectroscopically the red 
glass permitted the passage of all the rays up to the line D, 
that is to say all the red and the beginning of the orange ; 
for the blue glass the violet, indigo blue and the beginning 
of the green. The tadpoles subjected to the experiment were 
caught the same day in the same pond and preserved for 

'Comp. Rend. Acad, des Sc. Vol. T.XXXVII. 
'Gimpt. Rend.. 1858. 

'""Quoted by J. M. Kder. lYber die cheni. Wirkungen d. farb. 
Lichtcs, Vienna. 1879. 

*Lercdde and Pautrier, Photobiologic et IMiototberapie. 



some days in a large white bell glass. They presented no 
differences of tail, size >r development. They were divided 
into three groups, one of which was placed in the red 
aquarium, another in the blue while the third was put in the 
white hetl glass to serve as a control. Oilier than the 
difference in the energy of radiation to which they were ex- 
I all other conditions were exactly the same. The food 
was the same for all and was provided by the water of the 
punth which filled the aquariums and which furnished infu- 
soria. Daphnes and Cyclops. The illumination was always 
bright, as the aquariums were either placed in the garden 
of the dermatological establishment or before the laboratory 
window. The intensity of the light employed ought to be 
considerable, as it is reduced considerably by filtration 
through the colored glass. When feeble diffused light is 
employed, it is equivalent to darkness in the centre of the 
aquaria, however thin the glass may be. 

At the end of a month there was the greatest difference 
in the tadpoles of the red and blue aquaria* In their book, 
Leredde and Pan trier present photographic illustrations, 
showing these d iffe rcnceSi In each of the aquaria one died. 
Of the three survivors in the red aquarium, they were all 
still in the tadpole state with their caudal membranes. One 
of them had two pairs of feet feebly developed and breathed 
by the pulmonary method, but the other two had no rudi- 
mentary members, moved themselves simply by their nuta- 
tory membrane and breathed by the bronchial method, the 
bronchi being covered by a cutaneous operculum, t >u the 
other hand the three tadpoles raised in the blue- violet light 
had no longer caudal membranes. They were represented 
only by a little stump in process of disappearance* Their 
two pairs of feet were completely formed and they respired 
well by the pulmonary method. The photographs showed 
these differences very clearly — on the one side there are true 
tadpoles almost analogous to fish, on the other true frogs 
almost completely adult. The experiments of Leredde and 
Pautricr were also made to show the greater activity in 


cellular division, which alone could explain the apparent 
differences and also to measure this karyokinetic activity. 
To this end a tadpole of a urodal bactrachian, the Trito 
Cristatus, was selected. This tadpole presents a caudal mem- 
brane which is excellent for the purposes of study. Al- 
though it contains a great number of chromatophores it is 
very little pigmented and so small that if it is carefully cut 
off and skinned in the direction of its thickness it is an ex- 
cellent subject for the study of the yellow elements, conjunc- 
tival cells, capillaries in formation and epithelial cells in 

Larvae of the triton were kept for three weeks in blue 
and in red aquariums. Their caudal membranes were then 
removed and the preparations colored with hematin-eosin. 
The preparations were then examined by the movable gradu- 
ated stage, as in examination of the blood, to establish the 
leucocytic equilibrium. Section by section was examined, 
counting 4,154 epidermic cells in the sections from the 
tritons raised under blue glass. In these they found 52 
figures of cellular division or a little over 1/79 of the cells in 
karyokinesis. Upon examination of the tritons raised in the 
red aquarium they counted 2,613 ce ^ s an( l ] 4 m karyo- 
kinesis, or about 1/186 of the entire number. 

Subsequent to their experiments they found that [akimo- 
vitch 1 had reported similar experiments in a Russian publi- 
cation with similar results. He also observed that the larva.* 
of tritons developed better in light than in darkness, and that 
the karyokinetic activity of tadpoles grown under different 
lights was sensibly greater under violet energy than under 
the energy of all the other frequencies. He made his obser- 
vations upon the bronchi rather than the caudal membrane, 

The conclusion is, therefore, reached that light exercises 
an incontestable influence upon the development of the higher 
organisms, and that in the phenomena of karyokinesis the 
violet is the most active. 

'Wcstnick obehestvenog liygieny. Aug.. itfgi. 



The Influence of Temperature in the Phosphorescence of 
Bacteria* — This phosphorescence is influenced by the sur- 
rounding temperature. If very high or very low the flu 
cence is prevented, even though the bacteria continue to live. 
The limits within which they live are wide, hot dependent 
amongst other things upon the te mperat ure. 

Forster 1 found that a pure culture of a salt-water bacte- 
rium retained its power of light production and reproduc- 
tion at o - Tnllhausen- succeeded in reducing a culture of 
photogenic bacteria to —\2 without the complete cessation 

uf phosphorescence. 

The Necessity for the Presence of NaCl to Insure PtlOfi- 
phorescence nf Bacteria.— It has hem shown by various ex- 
perimenters, that all the light-giving bacteria require quite 
a high percentage of NaCl in the culture medium in order 
to be able to produce light The water of the sea is, there- 
fore, particularly suitable for the preparation of the different 

Two theories have been adduced with regard to the light 

production of bacteria: 

i. The production of light is a direct function of living 
protoplasm, and, therefore, just as inseparable from it as 
heat production. 

2. The living cell produces and gives off a substance 
(pbotogen), which outside the cell is luminous. 

Dubois* claims to have found such a pbotogen even in 
crystalline form, and Ludwig 1 asserts that, in the c;i 
the micrococcus pfluegcri, it is not the colonies themselves 
but the products of metabolism, which give off Light. All 
other researches with regard to pbotogen have led to nega- 
tive results, and the theory mentioned under 2 can, there- 
fore, not be considered as proven* 

In general it may be said that light has no effect upon 

'Centralis, f. Bakteriologte, 11. s. 337. 

Vittersucniifigei] fiber Bakt phosphorcscens Fischer, Diss. 
Wiirzburg, [88 

"CompU- Rendus <Je ('Academic des Sciences, Bd. CVIL, s. 502, 
'Centralbl. 1" Bakteriologie, Bd. II., s. 40, 


the phosphorescing power of bacteria, only Dubois 1 men- 
tions a diminution in light production in bacteria that have 
been exposed to light for several days. The fact that the 
ignis fatuus can take on such extreme forms in the tropics, 
even when the sky is cloudless for days, would indicate that 
at least one form of light-producing bacteria possesses a com- 
paratively great resistance to sunlight. A study of the ac- 
tion of concentrated electric light on these forms would be 

The Action of Light on Vaccine, on Bacteria, Toxins, 
Enzymes, etc. — Finsen and Dreycr 2 have experimentally 
shown that light, and especially the ultra-violet rays, can 
weaken or destroy smallpox vaccine. The vaccine was 
placed in drops on plates of rock crystal and exposed to 
concentrated light from an electric arc light of 25 amperes, 
50 volts ; the action of the heat was hindered by sprinkling 
with cold water, and the results were found by vaccinating 
children with it thereafter. An exposure to light lasting 
more than 10 seconds showed plainly a loss of strength in 
the vaccine, while an exposure of about 200 seconds was 
required to render the vaccine incapable of producing pus- 
tules. A prodigiosus culture was devitalized by the same 
illumination inside of 40 seconds. With illumination through 
blue or clear glass, which kept back the ultra-violet rays, the 
destruction of the vaccine was accomplished only after 15-20 

On the toxins of bacteria and all enzymes, which so far 
have been examined in this respect, light exerts a very de- 
structive action. 

Tizzoni and Cattani 1 found that long-continued action 
of sunlight not only is able to destroy the tetanus bacillus, 
but also to render inert the tetanus toxins. This destruc- 
tion took place most rapidly, when there was access to the 
oxygen of the air. These experiments were verified by those 

! Loc. cit. 

'Mittcilunfccn aus Finsen's Med. Lichtinstitut. 1903, Heft III. 

•Archives f. Exper. Pathologic, ifyo. XXVII. 


of Permis and Ccllis, 1 according to which the tetanus poison 
completely loses its toxic action after exposure to sunlight 
for several days. Later experiments showed a similar con- 
duct with regard to the toxins of other bacteria. 

With regard to enzymes, Dowries and Bhmt, 2 who also 
included this subject in their extensive and adnurabh 
searches, found that tnvertin was destroyed in sunlight, so 
that it lost its power to convert cam sugar. 

Green 4 has shown by unusually delt< < riments the 

destructive action of light on the dtastatic enzymes occurring 
in the leaves ol plants. This action is derived from the 
ultra-vinlet rays, while the blue, and especially the red rays, 
ss a favorable action, in so far as they are able to con 
\< Ti the t) Riogeti of the diastase into an active form* 

Schmidt-Nielsen* undertook lately in the above-men- 
tioned laboratory a series of experiments with regard to the 
action of light on ehymosin I 'rennet ). lie exposed it to 
light in small chambei walls consisted of quartz, and 

used as a standard of measurement (for the action of the 
light) the time required by o.i cm." enzyme solution to 
coagulate 10 cm/ milk at a temperature of 37°, Non-con- 
centrated electric light and sunlight had very little influence 
on the thymosin, while a very short exposure to concen- 
trated electric light lengthened the coagulation time quite 
materially. The action was ascribed to the ultra-violet 
rays, and the insertion of a piece of clear glass was suffi- 
cient to prevent this action. When the ehymosin, after il- 
lumination, was kept in the dark an after effect was plainly 
ed after one day. 

An attempt to make the enzyme sensitive to the rays 
which can be seen, by the addition of a sensitizer (erythfo- 
sin) gave negative results. As above mentioned, however, 

'kef in Cctttraltt. f. BakkriolnLno. 1S9J. XII , No. 18. 

f ol . 1 Royal Societj of London, Vol. XXVIII, , 

'Philosophical transactions of the Royal Society <>f London, 
1S97. Vol. CLXXXVII1 . 1, r67-ig 

Mitteilungcn aus Finsen'j Med. Ltchtinstttut, 1904, Heft IX. 


which was iflmninaied ar. : :he -ther half dark. :ha: they 
would always try to ge: : the bright -art. 

With animals, as with plants, there are those which in- 
stinctively seek shady ar.d dark r'ac^s. seemmg t; have an 
instinctive dread of light. 

It has been shown that animals are by the 
different frequencies of the spectrum, that is. they h.ave .• 
color sense. Finsen showed that earwigs. v\_vd-hce and 
earthworms are very sensitive to the short waved frequen- 
cies — blue violet — while Gn:ber. whose experiments h.ave 
been quoted, showed the same for the earthworm, even Mind 
ones like the triton. being extreme!) sensitive to this part 
of the spectrum, seeking refuge either in darkness or :n the 
long and slow waved frequencies of the red. as opportunity 
offered. The preference for blue violet by butter rhes was 
experimentally shown by Finsen. and is a matter of common 
observation to the student of nature. 

It has been, therefore, very completely demonstrated 
that the shorter and higher frequencies are much more 
strongly phototaxic than the longer and slower. The latter. 
if not present to too great a degree oi intensity, produce the 
same effect as darkness. The phenomena are not always 
uncomplicated. They are influenced by the supply oi oxygen. 
In the presence of sufficient oxygen the stimulus oi light 
energy is ineffective in Farannecium bursa ria and the ob- 
verse when the supply is insufficient. Temperature also in- 
fluences the phenomena. For example, phototaxic phe- 
nomena only appear in some instances if the temperature is 
raised at the same time. The phenomena are dependent upon 
the intensity of light, many animals reacting only to changes 
or to fluctuations in its intensity. 

Jacques Loeb 1 in a series of very care fully -conducted 
experiments on nearly ioo varieties of animals, in 
eluding caterpillars, butterflies, plant lice, ants, fly larv;e. 
the larva? of beetles, various hvbrids, etc., demonstrated a 

*Der Heliotropismus dcr Tlnerc und seine ri'lu-mnstiminung 
mit dem Heliotropismus dcr Pllanzcn. Wiirzburg, i8yo. 


still mure deep and intimate human relation of a sanitary 
nature, for an abundance of light energj is a necessary o mdi 
tion of mental and bodily well-being. The recognition of its 
Oonk psychical power is universal; the practical application 
nut always made. In all properly organised peoples there is 
a tove of light, and a fear of darkness is not confined to 
children. The sense of powerlessness, danger and alarm 
which the latter induces is shown by adults as well. Light 

energy is essentia] for al! the purposes of life, for the supply 
of oxygen upon which existence depends. It is a universal 
stimulus. When it falls upon the eye there are established 
functional activities in the hrain which are associated with 
intellectual and emotional states. That the hlue frequencies 
exercise a depressing effad and the red an exciting effed 
Upon the hrain seems well established : hut in this connection 
it is neither the one nor the other which is considered hut a 
complex of all the f requeues n's nun mixture the 

white lii^tit* that envelops us with its all-pervading em 
which is the normal psychical atmosphere. Variations in its 
intensity have in all probability widely different constitu- 
tional effects. But although the quality and intensity of tight 
energy demanded by the individual living organism may 
vary, the need lor it and dependence upon it is imperative 
for all. 

The influence of solar light as a disinfectant is chiefly 
upon the surface of translucent or opaque bodies. An) 
medium which cuts off the chemical frequencies from the 
blue into the ultra-violet region, as glass, dost and fog, as 
well as a clouded atmosphere, prevents this disinfectant 
process, so necessary to perfect hygiene and sanitation. 
Consecutive days of rain, mist and fog give an opportunity 
for the growth and development of pathogenic organisms. 
They usually are followed by epidemics more or less severe 
of the diseases dependent upon the activity of these germs. 

Houses that are closed for several months in the year 
should he left with the shades all up and curtains looped 
hack, in order thai the sunlight may penetrate every nook 


Chemical Rays Promoters of Energy. — In conclusion 
Finscn says that "all this demonstrates the biological impor- 
tance of the chemical rays, which are veritable promoters of 
life and energy/' 

Raphael Dubois 1 has shown that in the case of Proteus 
Anguineiis, which lives in the grotto of Adelsberg, the entire 
skin possesses the property of being excited by the luminous 

The Action of Light Energy in the Stimulation of Un- 
striped Muscular Fibre. — This has been the subject of 
research and experiment and it was shown by Arnold 2 and 
Steinach 3 that the incidence of light without heat causes 
contraction of the pupils in the excised eyes of amphibians 
and fishes. The sphincter of the iris, which narrows the 
pupil by its contraction, is composed of smooth muscular 
fibers containing a brown pigment. Even the iris of the eel 
when cut out and placed in normal saline solution contracts 
to light, the green and blue frequencies being the most 
active. This action is independent of the central nerve sys- 
tem and takes place even though the retina has been re- 
moved. The evidence points conclusively to a direct action 
upon the smooth muscular fiber, i.e., upon the cellular ele- 
ments. The importance of light as an excitant to the ner- 
vous system is not minimized by ascribing a place to the 
direct action of this agent upon cellular elements. 

Other investigators in this field are Brown-Sequard, 
Heinrich Miiller, 4 Reinhardt and lUulge. 

The phenomenon is regarded by I>rown-Scquard as 
direct muscle irritation by light. For a period of 30 
hours after death Harless 5 observed upon human corpses 

! Sur la perception des radiations luminenses par la pcau. chcz 
les Protees aveuglcs <lcs grottos de la Carniole. C. R. Acad, des Sc, 
t. CX., 1800. p. 100. 

*Landois and Stirling. 

'Untcrsiicliungen zur vcrglcichenden Physiologic dor Iris, in 
Pfliiger's Archives, Vol. LI I.. 1K92. 

M^andois and Stirling 

*Abhdlgn. d. bayr. Akad ., iStS. v. p. 490. Qnoteo by Freund. 


The Action of Light Energy upon the Higher Organisms* 

Introduction. — There is in animals as in plants a stimu- 
lating influence on the functions of tissue dements and 
ms by the action of light The impa nation of energy to 
the living organism is transferred into a stimulus by which 
all the vital processes are quickened and heightened. There 
is produced by this stimulus of light either a direct influence 
upon the irradiated protoplasmic cells, or there is brought 
about indirectly, through the sense organs and nerves, cer- 
tain functions on the pan of given organs. 

The Influence of Light upon the Development of Ani- 
mals and Man* — The development of many animals is de- 
pendent nn light and without it development proceeds slowly 
or is suspended altogether. It was observed by William 
Edwards 1 that frog spawn in an opaque glass died, while 
spawn in a transparent glass hecame duly developed* 

Tadpoles develop mnre slowly in the dark than in tin 
light. SchnetzlerV experiments prove that white light is 
more favorable to such development than green. 

The degree of development of animal organisms is influ- 
enced di ffe r e ntly by the different frequencies of the spec* 

"I>i- I'miiii' agents physique mr 1 n vie, P;iHs, 1824. 

'Archives dei Sc PI et Naturetles, 1S74, Vol LI. 


nus which naturally is white. Upon transportation to the 
light, these animals toward the second month presented a 
blackish-green mottling of the integument, soon deepening 
in confluent spots, resulting in uniformly coloring the animal 
a greenish brown. 

Bohn 1 in a study of the evolution of pigment conclude! 
that "in many cases the molecular constitution of pigment 
can be changed directly by the luminous waves of different 
lengths." "Until now, a purely alimentary origin had been 
attributed to the substances which color so variously the pig- 
ment of the caterpillar." 2 

Protective Role of Pigment against Light. — Of this 
action the chameleon is a noticeable e cample. The Vienna 
physiologist Briicke, 3 50 years since demonstrated the 
color scale through which the chameleon would pass on 
changing from light to darkness. 

The chameleon has in the depths of its integument large 
pigmented cells, or chromatophores, which are particularly 
mobile. In the dark these rest in the depths. Under the 
influence of light, the color changes from a gray to almost 
a black, illustrating their ability to migrate from the depths 
to the surface and again to the depths. 

Briicke showed that the movement of the chromato- 
phores is dependent upon the central nervous system. Dark- 
ness acts on the skin of the chameleon as a stimulant, while 
daylight, even sunshine, reduces the pigment cells to a passive 
state. When the chameleon is brought into the sunlight it 
becomes dark by projecting the elongations of the pigment 
cells to the surface of the body. When thev are taken into 
the dark the animal becomes pale in color because of the 
drawing back of the dark elongations of its pigment cells. 
so that they are covered by the light-colored pigment in the 
upper layers of the cuticle. 

"L'Evohition du pigment, ParR Naud. iqoi. 

8 Lercddc and Pairtritr. 

HJntersuchnngen iiber den Farhmwcchsel des Chameleons. 
Bericht dcr mathemat. Nalurwissenschaftl. Kla se 1). K. Akad. 
dcr Wisscnschaft. Wien. 1852, IV. 


The Action of Light Energy upon the Higher Organisms. 

Introduction, — There is in animals as in plants a stimu- 
lating influence on the functions of tissue elements and 
tut by the action of light. The impartation of energy to 
the living org&Ilism is transferred into a stimulus by which 
all the vital processes are quickened and heightened. There 
is produced by this stimulus of light cither a direct influence 
Upon the Irradiated protoplasmic cells, or there is brought 
about indirectly, through the sense organs and nerves, err 
tain functions on the part of given organs. 

The Influence of Light upon the Development of Ani- 
mals and Man. — The development of many animals is de- 
pendent on light and without it development proceeds slowly 
or is suspended altogether. It was observed by William 
Edwards 1 that frog spawn in an opaque glass died, while 
spawn in 8 transparent glass became duly developed. 

Tadpoles develop more slowly in the dark than in the 
light, SehnetzlerV experiments prove that white light is 
more favorable to such development than green. 

The degree of development of animal organisms is influ- 
enced differently by the different frequencies of the spec- 

'De t'itifhieticc des tgetiti physique snr la vie, Paris, 1824. 
'Archives des Sc Physiques et Nut u relies, 1874, Vol LI. 


It was observed by E. Yung 1 that violet light helped 
on the development of the embryo of rana, salmo, and 
lymema, which was hindered or disturbed by other parts of 
•the spectrum or by darkness. 

Beclard 2 observed that flies' eggs develop more quickly 
under blue and violet glass than under red, yellow, green 
or white. 

Guarinonr 1 from his experiments believes that violet light 
acts more favorably on silkworms ; while Goodnew noticed 
that maggots are much more quickly developed in pieces 
of meat exposed to the light than in meat kept in the dark. 
In his study on the activity of light on polypi Loeb found 
that the growth is not es]>ecially influenced by all the rays, 
but that only the more refrangible, that is, the blue rays, 
promote growth. The same effect on the other hand is pro- 
duced by red in darkness. 

Recently Leredde and Pautrier 4 have made a study of the 
development of animals under the influence of the energy of 
different parts of the spectrum. As subjects of experiment, 
tadpoles of the common rana tenij>oraria were used. The 
solar spectrum divided into two parts was used ; the one 
comprising all the energy from the green, blue, indigo and 
violet, and the other the energy from the red. Two aqua- 
riums were constructed, one of photographer's rod glass, col- 
ored with proto-oxide of copper, and the other of blue glass 
colored in cobalt blue. Each was covered with a glass of 
the same color as the aquarium, leaving just space enough 
for oxygen renewal. Examined spectroscopically the red 
glass permitted the passage of all the rays up to the line D, 
that is to say all the red and the beginning of the orange; 
for the blue glass the violet, indigo blue and the beginning 
of the green. The tadpoles subjected to the experiment were 
caught the same day in the same pond and preserved for 

'Comp. Rend. Acad, des So.. Vol. LXXXVII. 
•Compt. Rend.. 1858. 

3 Quoted by J. M. Kdt-r. Ueber die chem. Wirkungen d. farb. 
Lichtes, Vienna, 1879. 

4 Lcrcdde and Pautrier, Phutnbiologie et Pliototbcrapie. 


enough, sufficiently concentrated and exposed f**r a sufficient 
length of time. 

From the chemical point of view the bactericidal pof 
of light energy is a phenomenon of oxidation. For its sue- 

tul action the presence of oxygen is necessary. 

The Production ol Light by Miero-c )rganisms. — It i 
matter of common knowledge that certain organic suh- 
stances, meat and fish, for example, especially salt-water fish, 
when the process of decomposition is first established, give 
off a more or fess phosphorescent light, which is naturally 
most plaint] visible in the dark, 

Hluger 1 was the first to observe that this peculiar phe- 
nomenon was an expression of the activity of micro-organ- 
isms. Since then Litdwig, 2 Fischer, 1 r»cijerniek,* Katz, 6 
Giard, rt and others have made pure cultures, and deserilu d a 
great number of photogenic bacteria. In this connection 
Fischer pointed out that even the ignis fat tins is to in 
plained as a bacterial phenomenon. 1 

The intensity of the light given out by the different bac- 
teria varies greatly: the color also may differ, being white, 
bluish or greenish. Fischer found upon spectroscopic ex- 
amination, in the case of one bacterial species, a continuous 
spectrum from the Ddine to slightly beyond the f i line with a 
maximum intensity between G and R The strength and 
extent of the ignis fatuus in tropical waters is a matter of 
common observation and description. The phospfa 
of micro-organisms may be so great as to permit of telling 
the time of day; while photographs of cultures have I 
taken by the light produced by themselves. 

•PiHigers Archives f d Gesamte Physiologic, Bd. X,, s, 27^ tind 
iM. XI . v ass, 

'Zeitschr. f Mikro*kopic I 

itschr. f. Hygiene it Enfektionskfsmkh., II, Centralblatt f. 
Bakteriologie, III. 

'Ko in fCoch's Jthresber iSofe 1. 18a 

ntralhlati fui Baktcriologie, IX 
ivi f in Centmlblatt f. ftakteriologie, VI 
'I 'hoc lights can, however, also i« produced h> other plu»to 

genie organisms! for example, h\ Pertdiois 

RACTER1A. 197 

Bacterial Lamps. — In this connection it cannot fail to in- 
terest the reader to quote from MolischV communication to 
the Vienna Academy of Sciences in reference to the photo- 
graphic and illuminating power of micro-organisms in which 
he said he had been able to photograph phosphorescent cul- 
tures of bacteria after an exposure of 5 minutes, by their 
own light. In order to photograph other objects by means 
of this bacterial light, he constructed a special bacterial lamp. 
This consists of a large flask, whose interior is lined with 
salt-peptone-gelatin, previously inoculated with bacteria. 
On the second day following the inoculation the lamps begin 
to glow with a beautiful bluish-green light, due to the phos- 
phorescent colonies growing within. These living lamps 
have the property of shining with undiminished intensity for 
two or three weeks, and then gradually diminishing in 
strength. Their light is sufficient to permit one to recog- 
nize the face of a person standing two yards away, to tell 
the time, to read a thermometer, or even large-size print. 
In view of the freedom from danger of such a cold light, 
its use in mining operations or in powder magazines may 
become of importance. ( )rganic light, particularly the rays 
emanating from glowing insects, such as the so-called glow- 
worm, has been made the subject of many ' investigations, 
and it was even asserted that this light has the properties 
of the Roentgen rays. Molisch, however, proved this view 
to be erroneous, as bacterial light acts just like ordinary 

The Free Access of Oxygen Necessary for the Phos- 
phorescence of Bacteria. — Of first importance among the 
necessary conditions for bacterial phosphorescence is the free 
access of oxygen. If the culture be in a solid medium only 
the upper layers are illuminated while a fluid medium on the 
contrary by shaking with air may be made luminous through- 
out its whole extent. 

'The N. Y. Sun. March 15. 1003. and the International Med. 
Magazine, Oct., 1903. 



The influence of Tcnipcrature in the Phosphorescence of 
Bacteria. — This phosphorescence is influenced by the sur- 
rounding temperature Jf very high or very tew the fluores- 
cence is prevented, even though the bacteria continue to live. 

The limits within which they live are wide, hut dependent 
aillOIIgSt other things upon the temperature. 

I -orster 1 found that a pure culture of a salt-water bacte- 
rium retained its power of light production and reproduc- 
tion at 0°. Tollhauseii- succeeded in reducing a culture of 
photogenic bacteria to — \2° without the complete cessation 
of phosphorescence. 

The Necessity for the Presence oi MaQ to Insure Phos- 
phorescence of Bacteria,— It has been shown by various ex- 
perimenters, that all the light-giving bacteria require quite 
a high percentage of NaCI in tin- culture medium in order 
to be able to produce light The water ol the sen is, there- 
fore, particularly suitable for the preparation of the different 

Two theories have been adduced with regard to the light 
production of bacteria: 

i. The production of light is a direct function of living 
protoplasm, and, therefore, just as inseparable from it as 
heat production, 

2, The living cell produces and gives off a substance 
(photogen), which outside the cell is luminous. 

Dubois 8 claims to have found such a photogen even in 
crystalline form, and Ludwig 1 asserts that, in the ca 
the micrococcus pfluegcri, it is not the colonies themselves 

but the products of metabolism, which give off light. All 
other researches with regard to photogen have led to nega- 
tive results, and the theory mentioned under 2 can, there- 
fore, not be considered as proven. 

In general it may be said that light has no effect upon 

'( Yntralbl. f- Bakteriotagte, IF. s, 337* 

*Untersuchttngei] fiber B;ikt, pbosphorescens Fischer, Diss 
Wiirzburg. 1K89 

'CYiiN|itrs Rendu* de rAcadcnn. ,u> s | CVII., > 502, 

'Central!)!, f. Bakteriologic, Bd II ,i |0 


the phosphorescing power of bacteria, only Dubois 1 men- 
tions a diminution in light production in bacteria that have 
been exposed to light for several days. The fact that the 
ignis fatuus can take on such extreme forms in the tropics, 
even when the sky is cloudless for days, would indicate that 
at least one form of light-producing bacteria possesses a com- 
paratively great resistance to sunlight. A study of the ac- 
tion of concentrated electric light on these forms would be 
. interesting. 

The Action of Light on Vaccine, on Bacteria, Toxins, 
Enzymes, etc. — Finsen and Dreyer 2 have experimentally 
shown that light, and especially the ultra-violet rays, can 
weaken or destroy smallpox vaccine. The vaccine was 
placed in drops on plates of rock crystal and exposed to 
concentrated light from an electric arc light of 25 amperes, 
50 volts ; the action of the heat was hindered by sprinkling 
with cold water, and the results were found by vaccinating 
children with it thereafter. An exposure to light lasting 
more than 10 seconds showed plainly a loss of strength in 
the vaccine, while an exposure of about 200 seconds was 
required to render the vaccine incapable of producing pus- 
tules. A prodigiosus culture was devitalized by the same 
illumination inside of 40 seconds. With illumination through 
blue or clear glass, which kept back the ultra-violet rays, the 
destruction of the vaccine was accomplished only after 15-20 

On the toxins of bacteria and all enzymes, which so far 
have been examined in this respect, light exerts a very de- 
structive action. 

Tizzoni and Cattanr* found that long-continued action 
of sunlight not only is able to destroy the tetanus bacillus, 
but also to render inert the tetanus toxins. This destruc- 
tion took place most rapidly, when there was access to the 
oxygen of the air. These experiments were verified by those 

l Loc. cit. 

2 Mitteilungen au* Fin sen's Med. Lichtinstitut. 1903, Tic ft III. 

'Archives f. Kxper. Pathologic, 1890. XXVI 1. 



which result in vision. Light allowed to act upon the retina 
for a long time, and especially if it be intense, causes fatigue 

of the retina, which begins sooner in the centre than in the 
periphery of the organ, This retinal fatigue comes on 
rapidly at first, but develops more slowly subsequently. 

It has been demonstrated by Kuhne 1 that the nature and 
the amount Of light influenced the condition of the hair-like 
processes sent down between the rods and cones, and also 
influenced the formation of pigment granules of the pig- 
mentary cells of the retina. 

In a frog kept for several hours m the darkness the pro- 
{■►plasm of these pigment cells is retracted, and the pigment 
gra&uks lie chiefly in the body of the cell and in the pr> 
near the cell. In a frog kept in bright daylight, the proc- 
esses loaded with pigment penetrate downwards between 
the rods and cones as far as the external limiting membrane. 
A retina that hns been kept in the dark changes its electrical 
Conditions when light suddenly falls upon it ; the electrical 
current which passes normally from the retina to the brain 
is made stronger. 

The max i mum of stimulation for the eye accustomed to 
darkness is found in yellowish -green close to the thallium 
line. ( )n the other hand the eve adapted to the light reacts 
most to the yellow D-line of the spectrum. 

It was proved by Engelmann that frogs from whose eyes 
light was artificially excluded reacted with contraction of 
the interior cones of the retina upon exposure of the skin of 
the bade to light energy. In this fact is to be found the 
proof that the stimulus of the light energy reaches the brain 
by a centripetal course, and is able thence to induce motor 

When the brain is removed, it has been shown by Buedin- 

■ hat this reflex action does not take place. From this 

the conclusion must be reached that this transformation of 

the light energy stimulus takes place within the brain itself. 

'Landois and Stirling. 


Stimulus of the visual areas may produce spectra. This 
phenomenon cannot be produced at will by all persons. Car- 
danus (1550), Goethe, Nicolai, and Johannes Miiller could 
produce spectra at will. 1 

It has been shown by von Helmholtz, 2 Rence Jones, 3 
Dupre and John Tyndall that the lens possesses the power 
of fluorescence to a high degree. 

Von Helmholtz, after cutting out all the spectrum, in- 
cluding the violet rays, succeeded in seeing the ultra-violet 
rays, which had a feeble grayish blue color. The heat rays 
in the colored part of the spectrum are transmitted by the 
media of the eye in the same way as through water. The 
existence of the ultra-violet frequencies is best ascertained 
by the phenomenon of fluorescence. As the media of the eye 
themselves exhibit fluorescence (von Helmholtz), they must 
increase the power of the retina to distinguish these rays. 
According to Briicke, ultra-violet f requencies are not largely 
absorbed by the eye. 

Tyndall found upon bringing his eye into a violet ray 
that he noticed a bluish white glimmer filling the space in 
front of him. This glimmer comes from the fluorescent light 
in the eye itself. The crystalline hue of the eye when looked 
at from without lights up brightly at the same time." It 
seems very probable that this peculiarity of the lens com- 
mon also to the vitreous body is the explanation of the 
ability on the part of some persons to perceive sensations of 
light under the influence of Roentgen and Recquerel rays. 
It is not impossible, as suggested by Freund. that electric 
stimuli of the retina and the optic nerve may have something 
to do with it. 

'Landois and Stirling, Text-hook on Human Physiology. 


"Medical Times and Gazette, London, Aug., i860, pp. 163-167. 


The Physical Effects and Biological Action of Light Energy. Skin, 
Circulation, Nervous System, Metabolism. 

The Physical Action of Light Energy. 

When a wave of any kind strikes an obstacle that is 
much smaller than the wave length, the wave gets by the 
obstacle without much difficulty. For example, an ocean 
wave of 60 feet in length is n t troubled by a stake one 
foot in diameter, by reason of the fact that 60 such stakes 
would lie required to make a wave length. The stake would 
throw no shadow behind it UpOfl the wave. When, hoWi 
the wave length is of the same order of magnitude as the 
obstacle, the wave does not get by unobstructed., but on the 
contrary is broken up, reflected or jostled out of existence 
by the obstacle. A one- foot stake at the mouth of an ocean 
river would stop waves of 3 or 4 feet in length, or 
cause a shadow beyond. When light of ordinary visible 
Wave length strikes a molecule which is a very minute 
obstacle, the wave length is long by comparison with the 
molecule and goes smoothly on with but little absorption! or 
else is smoothly reflected with but little absorption; but 
when ultra-violet light is used, the wave length is sufficiently 
short to make the molecule, or molecule groups, interfere 
with and break up the waves, more or less. This breaking 
tip of waves involves imparting energy to the molecules and 
possibly the disruption of molecules with that energy. The 
higher the frequency of the oscillating light corpuscles the 
more likely this is to occur. Groups of molecules are much 


more likely to be affected than individual molecules, just as 
a disruptive action would \ye more marked from the impinge- 
ment of waves of suitable length upon a group of persons 
than upon a single individual, that is, in the jostling and 
general shaking up to which they would be subjected. The 
individual might be passed by as the individual molecule by 
the longer wave lengths. It is possible that there may be 
some particular sympathetic resonance between atoms and 
light frequencies, as, for example, between oxygen atoms 
and ultra-violet light frequencies. 

The* following theories and facts are generally accepted 
throughout the scientific world to-day, and help to elucidate 
the problem of the action of vibratory energy. All matter. 
whether organic or inorganic, is in a state of continual 
motion as regards its molecular or atomic structure. As we 
go up or down the scale this motion increases or decreases 
as we go up or down the temperature scale, until it theoreti- 
cally ceases at absolute zero. The motion is vibratory and 
depends, so far as its changes are concerned, upon the vibra- 
tions in the radiant energy acting upon the body of which 
the molecules are constituents. When the vibration is of 
sufficiently high frequency, the molecules break down into 
simpler forms, and the more complex the molecule, the lower 
is the frequency of vibration necessary to produce this result. 
In the ethereal vibration of radiant energy, the temperature 
of the body is raised. This Bean 1 regards as proof that one 
form, at least, of molecular vibration is induced by an 
ethereal vibration. The physician's conception of light 
should not be from the point of optics and concern the 
visual frequencies only, i.e., from and including the red, to 
and including the violet, but must embrace the invisible part 
of the spectrum also. That mysterious region known as the 
ultra-violet is of equal interest to the physicist and physician, 
as is also the invisible region below the red. 

'William FT. Bean, Ph.D.: A theory as to the Roentgen Ray 
Action upon Malignant Neoplasms. Advanced Therapeutics, May, 

226 LHJIH 

According to Lang ley. fcfae energy of the spectrum is con- 
tained as follows 

Hira-violet region i/ioo 

Visible . .«..,.. ig i oo 

Thermal beyond lh« red &o too 

]>ut as the visible contains much beat, the energy palled 
light is after all very small. It is an established ientific 
that man) chemical actions will not take place until a 
certain temperature is reached, which means the attainment 
of a certain molecular vibration period. Others again urny 
be brought about by exposure to tight, which may of may 
not change the temperature, bul which manifestly must have 
influenced the molecular vibrations. This action is shown 
to vary with the different parts of the spectrum. Photobi- 
has established, for example, a bactercidal action for 
the middle third of the ultra-violet region, the ability to ex- 
eile tissue reaction also to the ultra-violet, but the exact 
locality not determined ; a quieting action upon the nervous 
system to the blue frequencies and apparently an increase of 
muscular power under their influence. There is also ap- 
parently an exciting or stimulating action upon the Her- 
ein from the frequencies of the red region. These 
varying effects are due to the varying wave lengths or the 
varying frequencies of vibration. From the action of a com- 
plex of all of the frequencies, there is an influence upon 
molecular activity. In considering the phenomena of the 
vibrations of sound and the laws governing it, it is well 
known that to produce a musical note, it is necessary either 
to strike the body capable of giving it out, or to have it 
placed where it may receive the influence of another vibrat- 
ing In -1\ For this latter effect, however, the vibrating body 
must be of the same pitch or an even multiple of it, and the 
vigor of the response depends for one factor upon the 
approach of that multiple to unity. 

Bean advanced the theory that a restorative change might 
be established in a pathologic cell-like cancer cell, for ex- 
ample, by which instead of being destroyed, its character 


may become so altered that it becomes again a normal cell. 
Such a change he attributed to the action of the Roentgen 
ray. A single X ray impulse is in every respect an ultra- 
violet light frequency, but there the similarity ends, for the 
oscillating corpuscles of ultra-violet light are rhythmic and 
continuous, while the X ray is a discontinuous, infrequent 
and solitary pulse. The proper atomic motion of a cell, for 
example, should be stimulated by being in synchronism with 
an ethereal vibration, whose period of vibration is the same 
or a n itiple of it. In this way. not only groups of mole- 
cules but single molecules should be affected. In the longer 
and slower frequencies, as represented by visible light, are 
unquestionably to be found the periods of vibrational activ- 
ity necessary to the maintenance of the living organism in a 
condition of normal health and function, but when it comes 
to be a question of diseased processes, a tubercular gland, a 
lupus patch, an organized exudate, associated with be- 
ginning degenerative changes, a sepsis, a syphilitic lesion, 
it seems necessary, judging from a knowledge of physical 
laws and physiologic action, as well as clinical results, to 
have the periods of vibrational activity not only that of 
groups of molecules, but also in sympathetic resonance with 
the periods of individual molecules or atoms. 

The author believes that the action of condensed light, 
of which ultra-violet frequencies are active constituents, in 
diseases characterized by deficient oxidation, the sub-cata- 
bolic diseases of Wakefield, is to be accounted for on physi- 
cal grounds by the fact that there is a sympathetic resonance 
betw r een the vibrational activity of the oxygen of the blood 
and the periods of ultra-violet frequencies. Tt has been 
established by Cornu that the ultra-violet frequencies from 
the sun are absorbed not by the varying constituents of the 
atmosphere, such as the watery vapor, but essentially by the 
oxygen and the nitrogen of the air. The swing of the oscil- 
lating corpuscles of the penetrant chemical frequencies 
have either the same periodicity or rate of vibrational ac- 
tivity as an oxygen atom, or are a near multiple of the nor- 


LIliH I I 

nial atomic action. In other words they arc in sympathetic 
resonance. It does not seem to admit of question but that 
the essentia] principle of chemical action and vital activity, 
viz.. motion, molecular or atomic, is one and the same thing. 
They blend almost imperceptibly, the one into the other, at. 
a very great many points. Granted, as the author has 
assumed, that the molecules of a body, either inorganic, 
organic or protoplasmic, have a motion dependent upon 
ethereal vibration, and that the atomic constituents of the 
molecules of these substances or bodies have a rate of vibra- 
tional activity or motion peculiar to the molecule to which 
they belong, then it follows that this rate of vibrational 
activity or atomic motion must be influenced by the right 
kind of vibrational activity of the ether. The range of this 
vibrational activity must be compatible with the integrity of 
the molecule itself. The breaking Up of the higher frequeno\ 
of the oscillating light corpuscles, as they encounter the 
swing of the oscillating atoms or molecules, results in an 
impartation of energy to the molecule, or there may be a 
disruption of the molecule as the result ^i that impartation of 
energy. It seems very probable that both physical actions 
take place from the administration of concentrated and in 
ly chemically active light frequencies in a process such 
as lupus vulgaris, for example. 

In the ability of the ethereal vibrations ni radiant energy, 
light and heat, to establish responsive or synchronous mo- 
tion in the molecule of a given cell, motion peculiar to that 
of the molecule in question, must be found the rationale of 
their action. The response of a given atom or molecule 
may be only sufficient to secure the proper maintenance of 
normal equilibrium, as under natural conditions of exposure 
1o radiant energy. But when intense chemically active light 
energy from near its source is localized and concentrated 
fef prolonged periods of time over a deluemati/xd region or 
lesion, something more happens than the normal responsive 
molecular motion of the molecules or groups of molecules, 
as is evidenced by the nature of the regressive and productive 


tissue changes as well as clinical results. If a cell is not 
irreparably damaged, then by the return of the normal 
atomic motion of its constituent, it Incomes the seat of re- 
newed life and activity. If the converse is true, the molec- 
ular agitation resulting from the action of the very short 
and high frequency light vibrations must still result in a 
stimulating action upon the surrounding undegenerated 
tissue tending to the absorption of the debris of degenerated 
cells. In the case of bacterial growth or abnormal cells, 
they are so agitated and worried by the jostling activity of 
the light corpuscles as to be compelled to deliver up their 
energy, and eventually arc put out of commission, as it were. 
To this end successive applications arc required as there is 
no question of immediate destruction of bacilli or correc- 
tion of abnormal cell activity. 

It was pointed out by Dean that the difference as re- 
gards activity is comparatively great between a cancer cell 
and an epithelial cell, while as regards constitution, com- 
paratively slight, and that the tumor cell represents a ten- 
dency to return to a more primitive form, rather than to an 
advance in the developmental scale. In this same connec- 
tion he states that a similar suggestion might be seen in the 
chemical phenomenon of physical isomerism. lie reasons, 
therefore, that the atomic movements of one are not greatly 
different from those of the other, and that an ethereal vibra- 
tion favorable to the one would be corrective toward the 
other, providing it were strong enough to affect it at all. 
which is not the case with ordinary light and heat in malig- 
nant processes. The ability of a given energy, the X ray 
or the higher frequencies of light, for example, to produce 
a return to the proper atomic motion of a cell, providing it 
had not wholly departed from it. is the physical explanation 
put forward by Bean for the effects produced by the X ray. 
In his opinion their action appears to be a corrective and 
not a destructive one. If the theory advanced by l>ean is 
correct, their action by reason of their physical character- 
istics is that of a sudden release of energy, which starts into 



activity the diseased cell or cells which have departed almost 
wholly from (heir proper atomic motion, just as a sudden 
noise arouses the quiet sleeper. 

The frequencies <>f fight energy, however, have not only 
the same period of vibrational activity, of a near multiple of 
the vibrational activity of the atoms of cells, hut ai 
rhythmic flow which renders them a safer molecular stimu- 
lant than the X ray, and one which should preferably be 
chosen in all conditions other than malignant, [ft some of the 
milder manifestations of malignant disease, the more superfi- 
cial epitheliomas, for example, the departure from normal 
cell life, or normal atomic motion is not so great but that the 

ods of the ethereal vibrations known as light can favor- 
ably affect them. 

There must be a different period of atomic motion tor 
a giant-celled sarcoma, for example, to that of a degenerai- 
11, requiring', so to speak, a more sudden and violent 
expenditure of energy than the latter. Nothing is U* be 
gained by knocking a man down when a soft word will an- 
swer the purpose. Similarly, a sudden and violent expen- 
diture of energy, as of the vibrational activity oi the X raw 
is lo be condemned when the synchronous vibration or sym- 
pathetic resonance of light frequencies will suffice. The 
former may and does produce dermatitis with necro- 

sis and an effect even upon deeper structures. This is un- 
questionably due to the violent action of X ray impulses. 
The poorer .the vitality or body condition the less is the 
power of resistance, and the greater the damage. Chemical 
light frequencies also produce a dermatitis, but one from 
which recovery is easy. These an- not powerful enough to 
produce responsive atomic vibration In the cancer cells, nor 
for that matter is the X ray, as we know and use it, in the 
more profound and deep-seated lesions of this character. 

As vel it is impossible to say just what periodicity of 
vibrational activity or frequency of light vibrations is 
quired to influence the periods of vibrational activity of the 
cells of different kinds of tissue. 


That this is largely theoretical is true, but from a knowl- 
edge of physical laws, it is a theory that seems very near 
the truth. It is the high and short frequencies, those of 
great chemical activity, which influence so profoundly cell 
action. In diseased processes other than malignant there 
may be no question of a departure from normal atomic mo- 
tion on the part of the atoms of a cell, only a more or less 
profound diminution of it. 

The atom which has ceased to swing or vibrate, as it 
were, is hopelessly extinguished, but just so long as there 
remains the slightest atomic motion, it is possible, by the 
action of an ethereal vibration of the right period, to stimu- 
late it into renewed activity until once more it enters into 
its normal motion. Tf waves interfere (and waves repre- 
sent definite periods of vibrational activity) by odd mul- 
tiples of half wave lengths, they destroy each other, or if 
they hit matter in these odd phases they destroy themselves, 
but if they strike matter in even phases they do an incredible 
amount of work. They sustain every activity on earth, and 
alone keep up life. 1 

Were light frequencies destructive they would destroy 
not simply inhibit bacterial growths. On bacteria outside 
of the living body they do possess a destructive power which 
indicates only that in the living organism the conditions of 
atomic vibration around them are of such a nature as to 
prevent the immediate loss of their own atomic motion. It 
seems rational to conclude from the nature of the physical 
action of the short and high frequencies of light, i.e., their 
jostling activity by which they agitate and shake up small 
things like atoms, involving also a chemical change, that 
the micro-organisms would lose sonic of their power or 
virulence, and that successive applications should ultimately 
deprive them of their energy, increasing at the same time 
the physiologic resistance of the organism, l'ean reasons 
that with the X rav thev would either take on an increased 

x Larkin : Radiant Energy. 


l.k.m ENERGY. 

growth or not be affected at all, anil that the former would 
indicate a responsive atomic motion and the latter simply a 
failure to respond, 

To ilk author's mind an inhibitory action seems more 
likely to ensue, in BO far as bacteria are concerned, By 
inhibition is understood a reduced or arrested nutrition, 
This is a result of the chemical change brought about by an 
undue atomic motion or agitation. 

The superficial cells of an ulcerating tumor do not, Under 
Ehese forma of vibrational activity, show any evidence of a 
destructive action: on the contrary, they present an ap- 
pearance of increased vitality- In developing his theory 
Bean states that probably only the younger cells are favor 
ably influenced by the action of the X ray. and that the 
mature tumor cells have probably BO far departed from 
their normal condition* i e., atomic motion, as to he unin- 
fluenced by an expenditure of en< ich as the X ray, 
that any changes to which they are subject will depend for 
the most part on the nutrition they receive. If the younger 
cells return to normal periods of vibration, and the older 
cells undergo nutritional changes, a shrinking or atrophy 
of the tumor mass will follow which is very often the 
a firm but smaller mass remaining at the site of the tumor 
When there is a complete disappearance of the mass, he 
believes it to be due to a phagocytosis, in connection with 
the atrophy, a condition winch at the time of his exposition 
of the subject he was attempting to determine by microscopi- 
cal studies 

There can be no question but that there is a similar physi- 
cal action of the chemical frequencies of light, since the 
physiological action and the nature of tissue changes estab- 
lished by its use are of the same order. But there is lack- 
ing the harsher effect, due in all probability to the more 
sudden and consequently energetic stimulus to atomic 
motion from the irregular and infrequent X ray impulses. 
The con ular vibration of steam cars, for example, 

is more tolerable than the jerking and jarring produced by 


the frequent starting and stopping of the street ear. Dif- 
ferent effects follow, and while the latter might he service- 
able to a sluggish, hepatic circulation, for example, it could 
not be advised for an essential neurasthenia. Jt is by reason 
of this difference in physical action that the frequencies of 
light energy are of no avail in malignant processes save in 
the more superficial conditions of comparatively recent 
standing. In recent conditions, the departure from the nor- 
mal atomic motion must be very slight, hence the brilliant 
results obtained. In this way then a restorative change may 
be established in a pathologic cell ; not in destroying, but in 
altering its character by restoring it to a normal period of 
vibration or atomic motion. This may follow the use of 
other forms of energy than light, or, as instanced, the X ray. 
It may and unquestionably does follow the exhibition in- 
ternally of some forms of medication of which strychnia 
is a notable example. The various frequencies of light 
vibrations produce without doubt varying differences in 
effect upon cells. 

The analgesia, which is produced by the concentrated. 
visible chemical frequencies of light, may be induced by a 
continuous, harmonious vibration, which, judging from 
effect, has served to tetanize as it were, and exhaust the 
motility of peripheral nerve elements. 

From the physical properties of light energy and its 
physical action upon a body endowed with a vito-chemical 
constitution, as is the living organism, follow chemical. 
osmotic, and molecular changes or physiological action. So 
far as the chemical end of the spectrum is concerned, this 
physical action seems a rational one. I hit for that matter 
all the visible frequencies are chemical as well as the invisi- 
ble beyond the violet, and the same is true at the other end 
of the spectrum. It is only that certain frequencies, i.e.. 
from the blue and above, are more intensely active in this 
way in relation to the living organism, at least so far as 
known. In normal conditions of the living organism, the 
higher chemical frequencies as used therapeutically in con- 



o nirated light energy, arc not essential tint onlv active as 
they exist in diffused sunlight. When physical condi- 
tions, as they relate td light and atmosphere, render them 
intensely active, and when the conditions of the living 

ganisrn render it especially vulnerable, i.e.. in conditions of 
more or less depressed vitality, untoward results follow, 
This is forcibly shown in insolation or sunstroke. There 
is some evidence also that in prolonged unbroken periods 
of sunshine, with atmospheric conditions favorable to more 
than normal diffusion of the chemical frequencies, i.e., less 
active absorption before reaching the earth's surface, that 
nerve and mental States, where predisposition exists, are pro- 
foundly and unfavorably influenced. In an experience ex- 
tending over to years among the insane, it was a matter of 
common observation, that an untoward influence was ex- 
erted over the mental state of patients under these physical 
conditions. In addition the greater prevalence of both 
suicide and homicide has been noted by the author over a 
period of 30 years, as well as by Others, during the prev- 
alence of such physical conditions. The question arises 
what is the influence at work to produce such an intent 
citability of the cerebral cortex or to so profoundly influence 
conditions of uerve depression. There must, however, be 
considered all of the physical conditions, not only that of 
radiant energy, hut relative humidity and atmospheric pres- 
sure as well. 

Is the cerebral cortex unduly stimulated especially in 
those predisposed, hi the frequencies of the red end of the 
Spectrum? Are the nerve centres unduly depressed by too 
profound activity of blue or chemical light? There seems 
enough evidence to find ground for the questions. S< me 
time the relation of all the observed facts as to the relation 
of health and disease to all physical conditions will be un- 
ravelled and formulated. Whether man with his peculiar 
constitution, his desires and aspirations will be any better 
off. physically, mentally or morally, for the knowledge, is 
another question. Still it is true that life has been greatly 


safeguarded against many conditions of disease by reason 
of a definite knowledge of the relation between cause and 

Be this as it may, the physiological action of light, and 
not only the need but the dependence of the human species 
upon it for continued existence, remains unchallenged. 
The theory and practice of General Pleasanton of "blue 
glass" fame was not without a scientific basis, building 
as he did his sun rooms with every eighth pane of blue. 
But in common with all new theories and practices, it 
failed of sufficiently accurate scientific knowledge and 
careful discrimination. To-day the unparalleled work 
of Finsen, as well as that of others, places us on surer 

Light energy causes contraction of protoplasm, and acts 
directly upon the blood, increasing thereby its oxygenating 
power. The periodicity of the vibrational activity of the 
higher light frequencies and their periodical relation to 
the vibrational activity of oxygen atoms, and also the 
fluorescence of the blood and of the lymph serum, furnish 
aboundant supporting and corroborative evidence of the 
physical and physiological action of light energy. This 
is further substantiated by the intimate relation existing 
between the normal organism and light energy, as well 
as by a very considerable experimental work and clinical 

The Decomposing Power of Light. — Tyndall showed 
that if a beam of solar light be sent along its axis through a 
wide glass tube containing a quantity of the vapor of nitrite 
of amyl. which prior to the entry of the beam was as invisi- 
ble as air, that upon the entry of light, a cloud precipitated 
on the beam. This is due entirely to the waves of lij;lit 
which wreck the nitrite of amyl molecules, the products of 
decomposition forming innumerable liquid particles which 
constitute the cloud. Many other gases and vapors are 
acted upon in a similar manner. This decomposition is not 
produced by the frequencies of the greatest energy in the 



solar fight. The infra or ultra-red frequencies could be 
gathered Up and sent through the vapor like a beam of light. 
hut though possessing vastly greater energy than the light 
frequencies, they fail to produce decomposition, To I 
this a suitable relation must subsist between the molecules 
and the electric vibrations or waves of light. The pho- 
tographer fearlessly illuminates his developing room with 
light transmitted through red or yellow glass; but be dares 
not use blue glass, for blue light would decompose his chemi- 

And yet the waves of red light measured by the amount 
of energy they carry, are immensely more powerful than the 
waves of blue, Tyndall pointed OUf that it was misleading 
to term the blue rays chemical, for, as shown by Draper and 
others, the rays that produce the grandest chemical • 
in nature, by decomposing the carbonic acid and water, 
which form the nutriment <d plants, are not the blue ones. 

When it is a matter of decomposing the salts of silver 
and many other compounds, the hlue rays are the most 
effectual. These short and higher frequencies or weak waves, 
as termed by Tyndall, can produce effects which the longer, 
slower or strong waves are absolutely incapable of causing 
by reason of their periodic motion. 

It is the accord between the vibrations of the voice and 
those of the strings of a piano which cause the latter to 
sound when singing with it. Were this accord absent the 
intensity of the voice might be quintupled without produc- 
ing any response. But when voire and string are identical 
in pitch, the successive impulses add themselves together, 
and this addition renders them in the aggregate powerful, 
though individually they may he weak. 

In a similar fashion the periodical strokes of the oscillat- 
ing swing of the light corpuscle accumulate until the atoms 
UpOtl which their tuned impulses impinge are jerked asunder 
and chemical decomposition ensun 

1 T v n d all; N t w F r;t gmctlts. 


The Action of Light Energy upon the Human 

The general action of light to-day rests largely upon 
hypothesis. From its principal action outside of the 
living organism and from the constitution of the latter, as 
well as from its known action upon plants and the lower 
animals, a certain amount of speculative theory is permissi- 
ble. One mode of action is, however, firmly established and 
that is the action upon the skin. The well-known physiologi- 
cal action of stimuli, chemical or mechanical, in exciting 
either direct or reflex nerve phenomena, in relieving local 
congestions, influencing absorption of inflammatory prod- 
ucts, need only be* instanced to indicate that if no other 
tenable interpretation is offered for the action of light upon 
the living being, the known action upon the skin offers a 
rational explanation of many of the phenomena produced 
through this agency. 

The action of light energy upon the skin, however, is 
scientifically established. It is certain, clear and precise and 
stands as a basis for future study and investigation of the 
action of light upon the general organism. 

The Action of Light Energy upon Normal Skins. — Tn a 
previous chapter the passing and occasional reaction of the 
chromatophores to light radiation has been considered. This 
is to be distinguished from the more or less permanent pig- 
mentation to be seen both in men and in animals and in the 
parts of the body exposed to the action of light. When 
the skin containing cells which produce melanin, a mela- 
notic brown pigment formed only by the cells and not by 
the interspaces (melanoblasts), is exposed to the action of 
the solar light, the melanin or pigment is developed there, 
from the more abundant nutriment received under the stimu- 
lus of the light energy to the cells. Tn this way the tanning 
of the skin in those exposed to the constant action of the 
light, is produce* 1. It may proceed to a sepia-brown color- 
ing of considerable permanency. Tn those constantly ex- 
posed to the action of light it never disappears. 



mal atomic action. Tn other words they arc in sympathetic 
resonance; It does not seem to admit of question but that 
the essential principle of chemical action and vital activity, 
mot ion, molecular or atomic, is one and the same thing* 
They blend almost imperceptibly, the one into the other, at 
a very great many points. Granted, as the author has 
assumed, that the molecules of a body, cither inorganic, 
organic or protoplasmic, have i motion dependent upon 
ethereal vibration, and that the atomic constituents of the 
molecules of these substances or bodies have a rate of vibra- 
tional activity or motion peculiar to the molecule to which 
they belong, then it follows that this rate of vibrai 
activity or atomic motion must be influenced by the right 
kind of vibrational activit] of the ether. The range of this 
vibrational activity must be compatible with the integrity of 
the molecule itself. The breaking up of the higher fiequenq 
of the oscillating light corpuscle*. i\ encounter the 

suing of the oscillating atoms or molecules, results in an 
impartation of energy to the molecule, or there may be a 
disruption of the molecule as the result of that impartation of 
energy. It seems very probable that both physical actions 
take place from the administration of concentrated and in- 
tensely chemically active light frequencies in a process such 
as lupus vulgaris, for example. 

In tire abilii ethereal vibrations of radiant energy, 

light and heat, to establish responsive or synchronous tax> 
tion in the molecule of a given cell, motion peculiar to that 
of the molecule in question, must be found the rationale of 
their action. The response of a given atom or molecule 
may be only sufficient to secure the proper maintenance of 
normal equilibrium, as under natural conditions of exposure 
to radiant energy. 1'ut when intense chemically active light 
energy from near its source is localized and concentrated 
for prolonged periods of time over a dehaematized region or 
lesion, something more happens than the normal responsive 
molecular motion of the molecules <«r groups of molecules, 
as is evidenced by the nature of the regressive and productive 


tissue changes as well as clinical results. If a cell is not 
irreparably damaged, then by the return of the normal 
atomic motion of its constituent, it Incomes the seat of re- 
newed life and activity. If the converse is true, the molec- 
ular agitation resulting from the action of the very short 
and high frequency light vibrations must still result in a 
stimulating action upon the surrounding undegcncrated 
tissue tending to the absorption of the debris of degenerated 
cells. In the case of bacterial growth or abnormal cells, 
they are so agitated and worried by the jostling activity of 
the light corpuscles as to be compelled to deliver up their 
energy, and eventually arc put out of commission, as it were. 
To this end successive applications are required as there is 
no question of immediate destruction of bacilli or correc- 
tion of abnormal cell activity. 

It was pointed out by Bean that the difference as re- 
gards activity is comparatively great between a cancer cell 
and an epithelial cell, while as regards constitution, com- 
paratively slight, and that the tumor cell represents a ten- 
dency to return to a more primitive form, rather than to an 
advance in the developmental scale. In this same connec- 
tion he states that a similar suggestion might be seen in the 
chemical phenomenon of physical isomerism. He reasons, 
therefore, that the atomic movements of one arc not greatly 
different from those of the other, and that an ethereal vibra- 
tion favorable to the one would be corrective toward the 
other, providing it were strong enough to affect it at all, 
which is not the case with ordinary light and heat in malig- 
nant processes. The ability of a given energy, the X ray 
or the higher frequencies of light, for example, to produce 
a return to the proper atomic motion of a cell, providing it 
had not wholly departed from it. is the physical explanation 
put forward by Hean for the effects produced by the X ray. 
In his opinion their action appears to be a corrective and 
not a destructive one. If the theory advanced by I Jean is 
correct, their action by reason of their physical character- 
istics is that of a sudden release of energy, which starts into 



activity the diseased roll of cells which have departed almost 
wholly from their proper atomic motion, just as a sudden 

. arouses the quiet deeper. 

The frequencies of light energy, however, have not only 
the same period of vibrational activity, or a near multiple of 
the vibrational activity of the atoms of cells, but also a 
rhythmic flow which rentiers them a safer molecular stimu- 
lant than the X ray, ami one which should preferably be 
chosen in all conditions other than malignant In some of the 
milder manifestations of malignant disease, the more superfi- 
cial epitheliomas, for example, the departure from normal 
cell life, or normal atomic motion is not so great but that the 
periods »>f the ethereal vibrations known as li^ht can favor- 
ably affect them. 

There must be a different period of atomic motion for 
a gtant-cetled sarcoma, for example, to that of a degenerat- 
ing cell, requiring, so to speak, a more sudden and violent 
expenditure of energy thai] the latter, Nothing is to be 
gained by kno man down when a soft word will an- 

swer the purpose. Similarly, a sudden and violent expen- 
diture of enev rf the Vibrational activity of the X raw 
is to be condemned when the synchronous vibration or sym- 
pathetic resonance of light frequencies will suffice. The 
former may and does pirn luce seven dermatitis with necro- 
sis, and an effect even upon deeper structures. This is un- 
questionably due to the violent action of X ray impulses. 
The poorer. the vitality or body condition the less is the 
power of resistance, and the greater the damage. Chemical 

light frequencies also produce a dermatitis, but. one from 
which recovery i^ easy. These are not powerful enough to 
produce responsive atomic vibration in the cancer cells, nor 
for th:it matter is the X raw as we know ami use it, in the 
more profound and deep-seated lesions of this character. 
As yet it is impossible to saj just what periodidtj 
itional activitj or frequency of light vibrations is re- 
quired hi influence the periods of vibrational activity of the 
cells of different kinds of tissue. 

the -:-:- 
vi t*".t! •■■"". ■** :i . 
'ler-rivc :r. 
the phv-i 
that \v:::: 

.::■.- X rv 

'I-arkfr. : K:.-: 




growth or not be affected at all, and that the former w 
indicate a responsive atomic motion and tin 1 latter simply a 
failure to respond 

To the author's mind an inhibitory action seems more 
likely to ensue, hi s<« far as bacteria are concerned Bj 
inhibition is understood a reduced or arrested nutrition. 
This is a result of the chemical change brought about by an 
undue atomic motion or agitation. 

The superficial cells of an ulcerating rumor do not, tsnder 
these forms of vibrational activity, show am evidence of ft 
destructive action: on the contrary, thej present an ap- 
pearance of increased vitality. In developing his theory 
Bean states that probably only th- r cells are favor- 

ably influenced by the action of the X ray, and that the 
mature tumor cells have probably so far departed from 
their normal condition, i.e., atomic motion, as to be unin- 
fluenced by an expenditure of energy < such as the X ray, 
that any changes to which they are subject will depend for 
the most part on the nutrition they receive. If the younger 
cells return to normal periods of vibration, and the older 
cells undergo nutritional changes, a shrinking or atrophy 
of the tumor mass will follow which is very often the CSSC, 
a firm but smaller mass remaining at the site of the tumor. 
When there is a complete disappea ranee of the mass, he 
believes it to be due to a phagocytosis, in connection with 
the atrophy, a condition which at the time of his exposition 
of the subject he was attempting to determine by microscopi- 
cal studies. 

There can he no question but that there is a similar physi- 
cal action of the chemical frequencies of light, since the 
physiological action and the nature of tissue changes estab- 
lished by its use are of the same order. But there is lack- 
ing the harsher effect, doe in all probability to the more 
sudden and consequently energetic stimulus to atomic 
motion from the irregular and infrequent X ray impulses. 
The constant regular vibration of steam cars, for example, 
is more tolerable than the jerking and jarring produced by 


the frequent starting and stopping of the street car. Dif- 
ferent effects follow, and while the latter might l>e service- 
able to a sluggish, hepatic circulation, for example, it could 
not be advised for an essential neurasthenia. It is by reason 
of this difference in physical action that the frequencies of 
light energy are of no avail in malignant processes save in 
the more superficial conditions of comparatively recent 
standing. In recent conditions, the departure from the nor- 
mal atomic motion must l>e very slight, hence the brilliant 
results obtained. In this way then a restorative change may 
be established in a pathologic cell : not in destroying, but in 
altering its character by restoring it to a normal jwriod of 
vibration or atomic motion. This may follow the use of 
other forms of energy than light, or, as instanced, the X ray. 
It may and unquestionably does follow the exhibition in- 
ternally of some forms of medication of which strychnia 
is a notable example. The various frequencies of light 
vibrations produce without doubt varying differences in 
effect upon cells. 

The analgesia, which is produced by the concentrated, 
visible chemical frequencies of light, may be induced by a 
continuous, harmonious vibration, which, judging from 
effect, has served to tetanize as it were, and exhaust the 
motility of peripheral nerve elements. 

From the physical properties of light energy and its 
physical action upon a body endowed with a vito-chemical 
constitution, as is the living organism, follow chemical, 
osmotic, and molecular changes or physiological action. So 
far as the chemical end of the spectrum is concerned, this 
physical action seems a rational one. I hit for that nntter 
all the visible frequencies are chemical as well as the invisi- 
ble beyond the violet, and the same is true at the other end 
of the spectrum. It is only that certain frequencies, i.e.. 
from the blue and above, are more intensely active in this 
way in relation to the living organism, at least so far as 
known. In normal conditions of the living organism, the 
higher chemical frequencies as used therapeutically in con- 



Pigmentation, fchc Skin's Protection against Light 
rgy. — Evidence of this is to be found in the dark, almost 
black coloring of peoples or races of tropical clinics where 
they are always exposed to Strong insolation, The pail 
the body exposed to the action of the light are always 
darken The same is true of animals. The curious fact was 
observed by Wedding 1 that light and parti-colored b 
cattle and sheep, when fed on buckwheat if exposed to sun- 
light broke OUt bl blisters. The parti-colored beasts showed 
the skin condition in the light parts; the dark parts remain- 
ing unaffected Beasts kept in the dark and fed on the same 
food remained healthy. Wedding smeared a part of a cow 
with tar. As a result the eruption only appeared upon the 
uutarred part of the skin. This is supposed by I app< iner to 
he due to the fact that through this food (buckwheat) sub- 
stances get into the body which are capable of lluoreso 
i.e., when exposed to the action of light they absorb energy 
of radiation at one degree and emit it at another. This 
action of fluorescent stimulation is considered more in detail 
in the chapter devoted to that subject. Freund- in this con- 
nection reports an interesting and corroborative instance of 
the protective action of the pigment of the skin against light. 
He came by chance upon a dark cotnplexioued man wh 

irs had had vitiligo patches upon the body ami face. 
This man after a long walk over the Grosslockner glacier, 
developed violent inflammation (erythema) in vicinity of the 
white patches on the face but in those regions alone. No- 
w here else was the skin affected. This protective pigmenta- 
tion may be acquired deliberately as was done by Finsen,' 1 
who painted a ring around his arm with India ink and then 
exposed the arm for three hours to very strong light, after 
which the paint was removed. The skin, which at first 
seemed quite norm ah showing only some redness at the 

'\ '* rli;mrlhmgen dci Berliner Gcsellschaft fur Anthropoid 

1K88, p 57 

Freund, Radiothcram and Phototherapy, p. \20, 
"Hospital stidende, July 5, 1 s* j j . Journal Physical Therapeutics, 

January 15, 1901. 


of the belt, became red and inflamed all over, save in the 
area covered by the ink, where it was white and normal. 
After several days the redness disappeared and the skin 
became pigmented all over the area which had been red and 
inflamed. He then exposed the same arm to sunlight as 
before but without the India ink belt, with the result of the 
white belt becoming inflamed while the pigmented skin 
around it remained unaffected. The experiment is a most 
conclusive one, the same arm and the same skin having 
been subjected to the action of the solar light. Different 
skins react differently and a comparison to be of scientific 
value should be made upon the same subject. This reaction 
is a matter of common occurrence in individuals in those 
parts of the body unprotected by clothing under the influence 
of strong solar light. In the use of light in the treatment of 
skin conditions, this pigmentation serves to prevent the same 
absorption by the skin and reaction from the use oi strongly 
chemical light in subsequent exposures as takes place in the 
first exposure. A practical point just here might be made, 
viz., to make a prolonged application at the first sitting in 
order to profoundly influence the pathological condition be- 
fore nature turns her armed force of melanoblasts against 
further exposures. Einscn's experiment not only proves the 
importance of the skin pigment as a protective against light 
rays, but affords at the same time an explanation of the much 
disputed point as to the reason of the color of the negro's 

Action of Light Energy upon Xormal Skin. — Acute 
lesions are thus produced clue to the action of light upon the 
skin. These may be induced by sunlight, solar erythema 
or by the action of electric arc light, arc light erythema. 

The Sunburn of Glaciers. — The phenomenon has been 
carefully described by DeLong, 1 Klutschack, 2 Xordenskiold, 3 

'The Voyage of tlir Jrainutn-, London. iSS*. 
*AIs Eskinis untrr <kn Kskinio^. Wim. 1SS1. 
J Dcn Andra DickM>n>ka Kxptditiom-n till Gn'mland. Stuklmhu. 



and Widmark. 1 After a course upon the ice of glaciers or 
in the midst of simws despite the very low ambient, and 
although not suffering from cold, tourists <>r explorers of 
mountain glaciers or of the north seas present phenomena 
absolutely analogous to sunburn. The condition is charac- 
terized by intense redness <d the skin, by beat, smarting, a 
sensation of burning, Tins is followed by a desquamation 
of greater or less abundance according to the extent of the 
original inflammation of the skin. 

Nature of Pathological Change, — The skin inflammation 
from a glacial burn is followed bj a deep lint evanescent 
brown coloring of the skin and differs from the normal 
production of pigment or tanning consequent upon the action 
of light. From a single exposure to intense solar or electric 
light there is produced by the action of the strong light a 
marker! hyperemia of the skin ; the plasma of the blood, in 
which hemoglobin is dissolved, finds its way out freely 
through the walls of the capillaries. In a short time the 
hemoglobin is deposited in the interstices of the tissue as 
golden yellow hemosiderin. This causes the brownish-yel- 
low color of the skin, which only disappears after this blood 
pigment has been absorbed, i.e., in a few weeks. 2 The pig- 
ment may also be developed from the red blood corpuscles 
directly. They may pass by diapedesis out of the walls of 
the blood vessels and shrivel up into pigment corpusc! 

Electric Arc Erythema. — This finds its counterpart in 
solar erythema or sunburn. The first observation of this 
action Upon t1i< skin reported was by Charcot;"' who ob- 
served it in two workmen. As a source of energy a Bunscn 
pile of 120 elements was used. The same evening they 
experienced visual troubles and the next day both of them 
presented an erythema of the face accompanied by a feeling 
of discomfort and tension. This erythema, identical with 
sunburn, was followed by desquamation. 

't\l« t elm 1 iiiilnss ck-s Lichtcs aid die Haut. Hygiea. Fest- 
Ehrmann, Wiener Med Wocbenschr, [got, No. 30. 

"ComrHcs Rendu* Soc dv Biol., 1 


Charcot voiced the opinion for the first time that the 
condition was due to the action of the more intensely chemi- 
cal rays. 

The Electric Sunburn of Workmen in Electric Plants. — 
Defontaine, 1 Maklakow 2 and Finsen 3 are quoted as having 
made observations as to the production of this phenomenon. 
It is of common note. 

There is also produced a similar erythema in workmen 
exposed to the influence of electrically operated furnaces, in 
electric welding for example. It does not matter what the 
source of light energy, whether the sun, an electric arc or an 
electric furnace, each time that the skin is exposed to the 
action of the intense chemical light energy, there are pro- 
duced the same lesions known as sunburn. 

Phenomena of the Reaction upon the Skin from the 
Action of Intense Light. — The phenomena of this reaction 
are an increased coloring of the skin from a bright to a 
copper red, a swelling of the skin accompanied by a burning 
sensation and pain. In consequence of the proliferation of 
the horny layer the processes are marked. From exposure 
to a very powerful source of light energy, the action is much 
more intense. Blisters are formed, larger or smaller, with 
ecthymosis and even more or less deep seated necrosis of the 
tissues. This may. when the action has been intense, be 
followed by a degree of ill health. This occurs in workers 
about powerful electric arcs of which in several instances the 
author has been personally informed. After a few days, this 
varies with different individuals, the skin becomes less red 
and the pigmentation increases. The swelling diminishes, 
the blisters dry up, and desquamation takes place, at first in 
large flakes, subsequently in smaller bran-like scales. The 
process is similar to that of scarlet fever. 

Time of Reaction. — This reaction to the action of chemi- 
cal light energy does not take place immediately. In this 

'Bull, dc la Sue. chir <k- Paris. IK-c. 1887. 

*Arch. d'ophthalnial. IX. 07, i88g. 

*Mit. aus Finscn's Med. Lys.. Vogel, Leipzig. 1900. 


uom i s 

respect it differs from the action of thermal energy. This 
takes place immediately but dies away quickly. 

The reaction from light has a latent period, as do the 
Roentgen rays, but with the latter it is much longer. The 
length of time required for light reaction to reach its height, 
depend* upon the intensity of the light energy. It is 
longed in proportion to the intensity of the light action and 
dies away slowly with desquamation and absorption of pig- 

Maklakow, Moeller and Finsen have experimented to 
determine the period of latency , as have more recently 
Leredde and Pautrier. Maklakow observed that the ei 
of a 15 seconds exposure to a powerful arc light (amperage 
not given) was not seen until after to hours. An exposure 
of the skin to the light energy for one minute showed dis- 
tinct circumscribed hyperesthesia after half an hour, redness 
appearing after 2 3-4 hours. From an exposure of the skin 
for 3 J minutes it became red m l r minutes and portions of 
the skin exposed for 5 3-4 minutes reddened after 3 minutes. 
The experiments of Finsen and Moeller confirmed those of 

Before the deduction of a law governing the duration of 
the period of latency the reader is invited to a study of the 
very complete experiments of Leredde and Pautrier * 

Histology of Solar Erythema. — Leredde and Pautrier 
made a biopsy (examination of tissue from the living sub- 
ject) at the level of the skin of the shoulder upon one of their 
friends who had contracted in boating a severe erythema ^r 
sunburn. The biopsy was done 3 days later, Macro- 
scopically. the skin presented onlv an acute erythema; the 
color that of a red crab. There was no cetlema or effusion. 

Wit li a magnifying glass places of separation, a sort of 

cleavage of the epidermis, were distinguished. When 
slightly magnified, the epidermis under the mtcroscpe ap- 
peared almost normal in disposition and thickness. The 

'Leredde and Pautrier, Pftotobiologie and Phototherapie. 


corneous layer was observed exfoliated in spots. There were 
no lesions of importance in the derma; it appeared richer 
than normal in cellular elements, and there was a distention 
of its connective tissue bundles. With a higher magnifying 
power the corneous layer was observed a little raised and 
separated from the granular stratum. It is leaf-like and ex- 
foliated by the supcriniixxsed layers. The granular layer is 
intact and formed of 2 to 3 layers of cells. No important 
alterations are noted in the rete mucosum. A spongy condi- 
tion was noted, and the intercellular spaces appeared slightly 
increased. Some of the cells presented the ctat cavitairc of 
Leloir. In the basal layer there were noted numerous 
figures of karyokinesis, much more than normal. The 
lesions of the derma were of slight importance. There is 
slight oedema; the connective tissue bundles are slightly 
separated, the vessels present a very evident state of dilata- 
tion. A slight lcucocytic infiltration, forming in spots, is 
observed. The connective tissue cells appear a little swollen 
and are a little more plainly visible than ordinarily. There 
is no karyokinesis observed, however. 

The lesions arc identical with those produced by the light 
energy of an electric arc, so absolutely similar that it might 
be supposed that the same agent had been at work. 

The skin of the forearm of one of the experimenters 
was exposed to the action of the light energy from a Lortet 
and Genoud apparatus. (In this country the Victor lamp 
is practically the same.) It was maintained regularly at 
15 amperes. Between the skin of the exposed arm and the 
arc itself the quartz containing water chamber intervened 
and the distal enclosing plate was used as a compressor. 
This consists of two quartz discs enclosing the water cham- 
ber, or instead of discs or plates focal lenses may be used. 1 
The experiment was conducted under the same conditions as 
a treatment of a dermatosis by the energy of the electric arc 
would be carried out, in order to determine microscopically 
the mode of action, i.e., the nature of the tissue changes upon 

^or description set Chap. XII. 

244 I I 

norma] skin. There was taken into account at the same 

time the differences which exist hetween the mo<le oi re- 
action of the healthy and of the diseased skin. 

The arc was maintained constantly at 15 amperes, the 
time at 17 minutes, and the distance oi the compressor from 
the are at 4 cm. Their examinations, "biopsies/ 1 were made 
frorn one-quarter of an hour after the exposure to a period 
as remote as 8 days. In this way they were able to UA- 
l"\\ the process step 1»\ step Fof all the examinations the 
skin fragments were treated with a saturated solution ot 
sublimate aiul fixed in parafline. The sections wen 
with hematin, with homatm-eosin, with hcrnatin and 
with orange, and with thtonin. 

First Experiment' — The macroscopic observation showed 
only a moderate roughening of the skin. Microscopically. 
no important histological modification was noted. The 
ni" 4 that could he observed was a dilatation of certain blood 
vessels, the lumen of which gaped when the vessels were cut 

Second Experiment, — Biopsy made 2 hours after the 
exposure. In this m< 1 k -ti there was observed at the level 
of the region treated a fresh erythematous tint and a very 
slight cedetna, with a very slight loss of epithelium at cer- 
i.iiii points. 

With a low power microscope lens there appeared but 
slight dermic alteration, while there was considerable alter- 
ation! in the epidermis, tending to end in vcsieulatiou. 

With a little higher power lens an oedema of the derma 
was observed slightly separating tissue bundles, and peri- 
vascular lvnij aces. There was also noted moderate 
cellular infiltration by the lymphocytes. Mast cells appeared 
In normal numbers. The important phenomena observed 
is a slight proliferation of the fixed cells, or rather a tume- 
faction whirl 1 renders their swollen protoplast ore sp 


These were the same lesions which were established by 
Leredde and Taulrier in the histology of sunburn. The 


epidermic alterations are more considerable. In places there 
is a partial exfoliation of the corneous layer ; and there are 
some cells that have preserved their nucleus. In the granu- 
lar layer there is an almost complete disappearance of the 
granules. This layer is represented by one or two layers of 
flat cells, scarcely colorable. There is an irregular disposi- 
tion of the cells of the Malpighian layer. Above all the 
spongoid state of Unna and the 'Hat caritairc of Leloir were 
noted. There is a varying intensity of the spongoid state 
according to the points observed. In places the cells are 
lightly sq>aratcd from one another and their filaments dis- 
tended, while in other points the more abundant exudate has 
pressed back the cells disposed around it, representing an 
embryonal vesicle. Very small subcorneous bulla* are noted 
at certain points, formed by the cleavage of the corneous 
layer in its union with the mucous ImmIv. Such bulla* are 
filled with granules and anastomosing fibrils, which seem 
to be of fibrin. 

The alteration cavitairc of Leloir is observed at every 
stage; the clear perinuclear space is soon increased, while 
the exoplasm is pushed back to the periphery of the cell. 
Next there is observed a curious alteration. The centre of 
the nucleus is deeply colored, around it is an ill-defined 
vacuole, then the protoplasm colored a pale blue by the 
thionin, and the whole floating in a little vesicle. Again 
the protoplasm seems to have disappeared, and there is only 
found the nucleus and some protoplasmic granules. In 
other elements the nucleus is no longer colored, and there is 
found no more than a skeleton of it. At another place a 
formed but minute vesicle with some cells of Malpighi quite 
regularly disposed around it. presenting upon one of the 
sides of the vesicle a cell already partly destroyed, is ob- 
served. The nucleus of the latter surrounded with a small 
band of protoplasm plunges into the vesicle, and is no longer 
held to the wall of the latter save by 2 or 3 protoplasmic 

Resume. — These lesions the spongoid and cavitary altera- 



tions exist as well at the base of the epidermis as at the 
superficial part. The corneous alterations appear, generally 
speaking, to be a great deal more important. As a rule the 
Malpighian eells are more voluminous than ordinarily and 
appear 1 iked with serum. Although in spots the 

Malpighian layer presents a certain thickening, no karyokine- 
tic phenomena are oh served. 

There is not noticed in connection with tin lesions just 
descril>ed any alteration of the hair follicles. They present 
no indications of having heen subjected to the action of light. 
Their epithelium is normal, and the fresh coloration by 
thiotlin IS in marked contrast to that of the rest of the 
epidermis, which was colored poorly. 

It was concluded by the experimenters that this preser- 
vation of the epidermis about these follicles ts due without 
doubt to the accumulation of corneous substance in the 
utricle which protects it. 

Third Experiment. — Biopsy made 4 days after exposure 
to Mie light energy. There is observed upon the point 
treated a brownish-red color and a soil of cl A the 

epidermis, which seems raised al certain points, without 

there being actual vesicles. With the microseojie the lesions 
of the epidermis appeared verj considerable while the der- 
mic reaction was but little marked. 

The Epidermic Lesions. — There were 2 very different 
cts to the epidermic lesions, depending upon whether 
a portion of the epidermis is situated under a India, or be- 
side one. If OUtstdc a bulla, the epidermis presented almost 
no colored nuclei, staining by thionin showing an inter- 
mediary coloration in blue and pale violet With an immer- 
sion lens, notwithstanding the cellular limits, and that the 
nucleus is replaced b\ a large hole (the vacuolization ob- 
served From the action of (1) Roentgen ray, (2) ultra- 
violet ray, and i \) high frequency discharges), the proto- 
plasm IS Battened and the fenestra of the mucous bodies en- 
1. Here and there persists 1 nucleus in general elon- 

gated perpendicularly to the epidermis and presenting an 


almost normal aspect. Above the altered mucous bodies there 
is no trace of the granular layer to be found. The corneous 
layer is quite thick and flaky. It preserves some almost nor- 
mal coloring reactions. It is noted, however, that in certain 
points there are found some readily colorable epithelial 
nuclei, with a distinct reticulation. The protoplasm all 
around is scarcely or not at all apparent. 

The epidermic lesions below the bulla are entirely dif- 
ferent in their aspect. There is found an epidermic layer 
which with thionin colors violet, and which shows on its 
deep face some papilla? and some intcrpapillary cones. This 
layer presents two superimposed zones of different aspects. 
The more superficial one is very thick, appearing almost 
homogeneous to a low power lens. With a higher power 
there are found some nuclei which appear like lymphocytes 
migrating toward the bulla and a tissue of hyaline appear- 
ance. Also here and there, a flattened epidermic cell is out- 
lined in turbid protoplasm. Some epithelial nuclei seem in 
contact with the bulla. The deep zone on the other hand is 
formed by an epithelium which has preserved its nuclei, and 
which is disposed in a single liver above the papilkc, while 
in many layers it is thickened to form the papillary cones. 

The large bulla is limited by an extremely thin corneous 
layer. It contains a liquid which colors in a homogeneous 
fashion, and which by the orange ("I forms a veritable orange 
lacquer, sprinkled with polynuclear cells ( eosinophils ) hav- 
ing large nuclei. 

There exists a zone of transition, between the part of 
the epidermis underlying a bulla and the epidermis around 
the bulla, where large vesicles near to one another which 
are not yet joined with the principal bulla are observed. 
There is seen at first a subcorneous vesicle which is formed 
in the same manner as the large bulla, of which it presents a 
miniature in which the phenomenon of diapedesis is not pres- 
ent. There is observed, however, an irregulrr mass con- 
sisting of necrosed protoplasm. The other vesicles are 
formed in the same manner, but are deeper, they have 



no regular limit, their walls arc formed by a necrose* 1 epithe- 
lium, having a vacant space in place of the nucleus, and pre- 
senting the coloring reaction already described. 

In this, as in the preceding experiment, a hair follicle 
comprised in the section preserved its integrity taking a 
riolef stain by thioiiin as in the normal state. 

The dermic alterations are a great deal less important. 
A frank vascular dilatation is noted, but curiously not of the 
cellular focus. The connective tissue presents a turbid state. 
There is a true tumefaction. Under the bulla are seen two 
papilla, filled with a homogeneous tissue, from which every 
I has disappeared. By the side of dilated vessels, there 
is a disappearance of certain others. A slight redema is 
also observed, also some eosinophiles in migration toward 
the epidermis where they are found, also here and there nut- 
side of every \v red globules are seen. 

( U this period, IjC. the fourth day, the gross alterations 
are epidermic, and it is impossible nol to be struck by the 
differences between the epidermis underlying the bulla and 
the epidermis situated around the bulla. Leredde and Pau- 
trirr find this difference hard to explain, but advance the 
following hypothesis : In the tissues altered by the action of 
the %ht energy, the influence ol tin external conditions 
must be much more important than in the normal stale, and 
that as much more as the dermic circulation i-; profoundly 
diminished, and as the perivascular changes are a departure 
from the normal. In these conditions it is fair to admit 
that wherever the epithelium is not protected it is desiccated. 
( )n the contrary, wherever there is liquid, the cells maintain 
their normal dimensions and are in a more favorable condi- 
tion of vitality. 

Fourth Experiment. — Biopsy made S days after the ex- 
posure to Kghl energy. Contrary to the preceding periods 
the epidermis is thick, much more so than in the normal 
strife. The derma presents quite important reactions which 
are proportional with those of a common inflammation. The 
thickening of the epidermis is due above all to "the existence 


of a layer underlying the mucosum, and which represents 
the granulosum profoundly modified. It is formed by the 
cells whose long axis is parallel to the surface of the skin. 
In numerous points these cells are confluent in a manner, 
indicating the formation of a homogeneous layer. They 
have very large nuclei, of the character of the nuclei of the 
mucosum, elongated parallel to the surface of the skin and 
often surrounded with a vacuole. There are observed in 
this layer some large granules of keratohyaline and numer- 
ous eosinophile cells and granules. Above this layer there 
is a solid stratum formed of corneous cells, of eosinophils 
and of nuclei, the origin of which cannot l>c determined. 
These crusts are covered by a thin corneous layer, forming 
a universal investment. The character of the rete mucosum 
is remarkable. It is formed of relatively small cells with 
a very large nucleus. The intercellular spaces of the 
interior of the rete mucosum are dilated, while in the basal 
region the cells arc heaped up one upon another, especially 
at the summit of the papill.T, where they are elongated and 
seem to naturally compress themselves. Tn all the thick- 
ness of the rete mucosum, but (..specially in the basal layers, 
there is found extensive karyokinesis in all stages. The 
preparation, observed the experimenters, could serve as a 
model for epidermic regeneration. There were no elements 
in diapedesis in the Malpighian bodies. The bisal layer of 
the latter presents no longer the slightest pigmentation. 
Every trace has disappeared, and the skin was normally 
very much pigmented in this subject. 

There is established in the derma, principally in the sub- 
epidermic part, the state of hyaline tumefaction that was 
remarked in the third period of the experiment, lhit there 
is found in this layer a greater number of vessels, even in 
the papillae. These are extremely dilated — even to the for- 
mation of veritable lakes of blood. These vessels arc bor- 
dered with endothelial cells, slightly numerous, but whose 
protoplasm much drawn out forms a wall. There are to be 
found in certain points in the endothelium of the vessels some 



figures of karyokinesis. All of these phenomena arc indic- 
ative that there are going Of) some phenomena of regenera- 
ti-in. Numerous hematin granules are found scattered out- 
the vessels. The connective tissue cells of the derma 
present a state of tumefaction which renders them more 
apparent and some are in karyokinesis. There are noted 
also here and there some lymphocytes, trying to form little 
rounded masses to occupy the lymph spaces. The mast cells 
are also a little more numerous than in the normal state, 
somewhat irregular in form, elongated and drawn out 

There is n< t only no trace of pigment in the basal layer 
of i he Mafpighian body, but there li also no trace of dermic 

Histological Reactions Late in Appearing. — The im- 
portant deduction from these experiments is the late appear- 
ance of the histological reactions. This slow reaction is 
specific id* the action of chemical light energy. In this it 
differs markedly from the reaction established by the ther- 
mal eoergj of fight In heat hums the lesions soon disap 

I rrund 1 in instituting a comparison between the effects 
produced upon the skin by chemical liglr thermal 

energy and that of the Roentgen ray, formulated the follow- 
ing laws a> to the speed with which the reaction shows itself 
and the length of its duration : { i ) The duration of the 
period of latency is in inverse ratio to the wave lengths of 
the active rays; in like manner the effect lasts longer in 
proportion as the wave length of the active raya becomes 
shorter, (2) The greater the intensity of the light the 
earlier floes the reaction show itself and the longer does it 
lit If the intensity is less the reaction shows itself later 
and lasts for a shorter time. 

Moeller- studied the subject of the action of light energy 
upon the skin, with a view <d" discovering what changes of 
tissue in the skin observable under the microscope corre- 

Radiothcrapy and Phototherapy. 

'Quoted 1 1 v f ; round. 


sponded to the various clinical pictures of ordinary sunburn 
as well as more severe reactions. In his experiments he used 
skin from his own forearm, also skin from the head and ear 
of rabbits. As a source of light energy electric arcs of from 
i f 200 to 1,400 normal candle-power were used. The same 
apparatus as that used by Widmark in his investigations as 
to the cause of the erythema produced by electric light, and 
similar to the Finsen tube, was used by Mocllcr, the circu- 
lating water absorbing the heat, permitting thereby the 
activity of the chemically effective energy. 

To secure various degrees of effect from a faint erythema 
with a consequent slight discoloration and pigmentation to 
the more marked changes of redness, swelling, formation of 
vesicles, necrosis, etc., the distance between the source of 
light energy and the skin to be acted upon and the time of 
exposure were varied. Repeated exposures of the same part 
of the skin to the action of the light were also made in fur 
therance of the same purpose. 

Histological examination was made of specimens taken 
from the dermatitis of various degrees thus produced and 
subjected to microscopical examination as follows: 

(1) Human skin after slight photo-electric er\thema 
had been produced. 

(2) Grayish toned thickened, rigid, but not yet pig- 
mented skin from the head of a rabbit. 

(3) Skin from an ear of an albinntic rabbit, hypenemic. 
(Edematous, dotted with little blisters. 

(4) The ear of an albinotic rabbit showing more marked 
change, swollen on both sides, hypenemic. showing ecchy- 
mosis and blisters. 

(5) A piece of human skin, on which a mulberry-shaped, 
irregular, dark red hemorrhagic blister had former] from 
exposure to the light energy. 

From a review of the microscopic changes found in these 
various specimens, 1-5, the following conclusions are 
reached : 

"The first change to show itself in tin- exposed skin is in 



the vessels, which become microscopically more or less 
dilated. In connection with this the epithelium b ecom e s 
moist throughout, and there is an abnormal formation of 
matter (parakeratosis of a changed darker color. The 
prickle-cell layer of tin epidermis and the horny layer appear 
much extended. Within the latter is a deep-colored strip, 
which OOfiBlStS of borfl cdls within their nuclei, Fig, 5. 1 

Moeller surmises that the skin, which shows miero>cnpi- 
cally no other change than a yellowish brown color, gets its 
color ftOOl the abnormal strip of nucleated cells. When the 
irritation produced by the light energy is more intense and 
of longer duration, exudation supervenes which is Sero- 
fibrinous or rich in cells; it may often also contain red blood 
cells. The deptfa to which the changes extend are in proper 
tion to the intensity of the light and the different nature of 
the skin exposed to the light, Le. f human or rabbit. 

The extent to which the pores are affected depends upon 
the intensity of the exudation. The collagenous tissue begins 
ell and becomes hon us* the epithelium swells, 

becomes relaxed, infiltrated and raised in bulla*. The inter- 
ruption of continuity occurs in various pin 

In the human skin it occurs approximately on the Iwder 
line between the granular and horny layers, but this, by no 
means, precludes the possibility that on Other occasions, i.e., 
with other skins and other degrees of light intensity, the 
bullous exudation may not arise differently. This would be 
analogous with the course of pemphigus for example, where 
in some cases the blisters appear between the cutis and the 
rete, in others between the granular and the horny 1 
With more intense light thrombi are formed in the vessels 
of the cutis 

"In Moeller's case the contents of the blister consisted of 
a fine reticulum, containing numerous red blood corpuscles 
and isolated leucocytes. Every when fchi surface 

numerous light, round blisters are to be seen with a more Of 

delicate covering membrane and a light centre. This is 

'Figs 6, 7, nn*! 8 from Frtninl, Radiotherapy and Phototherapy. 


shown in Fig. 7. In some of the horn cells, loosened 
from the covering of the bulla?, may be seen very distinctly 
through the swelling of the cells, a longish rod-shaped hole 
in the centre in the place of the nucleus. In the remaining 
prickle-layer, too, which forms the base of the blister, cell 
changes occur, which vary from a simple swelling to a 
bullous degeneration/ 1 as is shown in Fig. 8. 

These experiments of Moeller's are a very complete con- 
firmation of those of Freund with the rabbit's ear as to the 
deeply penetrating action of the ultra-violet frequencies. 
"The disturbances were, when the light was very intense, 
most marked and also on the reverse side of the cartilage. 
in fact because of the larger number of vessels on that side, 
they were more noticeable there than on the directly illu- 
mined side." 

Moeller in his investigations proved further that when 
both thermal (50 to 55 ) 1 frequencies and intense ultra- 
violet frequencies were together active from the source of 
radiating light energy, they produced, as did the thermal 
frequencies alone when the ultra-violet were filtered out, 
more or less cerebral disturbance, sometimes even sudden 
death. Subsequent to intense radiation of that nature, the 
autopsy showed the skin of the head to be much swollen and 
a bloody gelatinous exudation to be present in the subcuta- 
neous tissue. There was discoloration of the periosteum, 
the cranial bones and the dura, while they were covered with 
ecchymoses. The vessels of the brain surface were much 
dilated and upon it were numerous and in part confluent 
ecchymoses. Upon filtering off the thermal frequencies and 
exposing the animal to the ultra-violet frequencies alone, 
there was no central disturbance observable. From these 
experiments Freund 2 concludes that the action of the ultra- 
violet frequencies at any depth is relatively unimportant. Xo 
change of tissue was to be seen, even in the spongy subcuta- 

! Not stated whether degrees Centigrade or Fahrenheit, hut 
probably the former. 


neous tissue, which is in direct contrast to the condition after 
exposure to the thermal frequencies 

There is caused by the act inn of both thermal and ultra- 
violet frequencies a hyperemia of the cutis. This, when pro- 
duced by the ultra-violet frequencies alone, is followed bj 
discoloration and hyperplasia of the epidermis, especial!) of 
the horny layer, which in turn prevents further penetration 
intn the tissu 

Pathogeny, — In the production of solar erythema and In 
electric light erythema, histological reactions of which have 
been given, the question presented bo the experimenter is 
what part of the spectrum is particularly lb is was 

lirst hypoihctically answered by Charcot, who placed it at 
the intensely chemical end of the spectrum. Bouchard 1 in 
his studies upon pellagra reached the same conclusion, 

That solar erythema and photo-electric erythema awe due 
to the chemical frequencies of the spectrum is then a funda- 
mental fact. 

In recent years this has been made the subject of exper- 
imental investigation and study by Widmark, Finsen, 
Freund, Bernard and Morgan, Each and all have arrived 
at the same conclusion, 

Widmark- was the earlier experimenter. lie analyzed 
the action of the different frequencies upon the skin, u 
for the purpose the shaven skin of a white rabbit and a 
water-cooled metallic tube quartz enclosed al one end, at the 
Other half by rock salt and half by glass* This apparatus 
used in connection with an electric arc. Through the 
side of the tube containing the rock salt, both with and with- 
out water, the typical erythema was developed followed by 
desquamation. This was no1 true <>f glass simply because 
of the physical inability of ultra-violet frequencies to pene- 
trate its substance. The experiments <>f Finsen* are very 

'Rechertftes Nouvelles iut la Pellagra, Paris, 1862, also Cbmptes 

lv« n.his Soc »K- Biol. 1S77 

"Hygiea, Feslband No. 3, iKK<; 

'Mitthcilungeii au Lj iinstiiut, Leipzig; also Journal of 

ical Therapeutics, Jan., E901. 


prettily illustrative. He utilized the flexor surface of his 
forearm, where the skin was very thin, placing upon it a 
plate of rock crystal and a series of bits of glass of different 
colors held in place by a few drops of glue. lie also marked 
the initials of his name in India ink upon the surface of the 
same forearm. He then exposed it to the energy of an 
80-ampexe arc for 20 minutes. For the first half of the time, 
10 minutes, he held his arm at a distance of .50 meter from 
the light of the arc, but as the heat was still very intense at 
that distance and as it could falsify the results he moved 
further away and for the last 10 minutes held it at .75 
meter. The bits of rock crystal and glass were then taken 
off and the India ink removed. The skin presented a slight 
redness where the enumerated objects had been placed and 
a uniform redness elsewhere. Two hours later the redness 
began to disappear, the coloring being uniform throughout. 
Three hours later there was an increased redness but only 
in the unprotected regions. And this difference between the 
protected and unprotected skin went on increasing until on 
the next day the forearm was deep red, hot. sensitive to 
pressure, while the parts which had been covered by the 
pieces of glass or by the India ink were white in coloring and 
absolutely normal. On the other hand that part of the skin 
surface covered by the rock crystal ( quartz) was red and 
hot as the unprotected part of the forearm. In several days 
this redness disappeared and was followed by desquama- 
tion, subsequently by very marked pigmentation which 
served as a brown base or background for the white spots 
which had been covered by the glass and the two letters, 
N. F. which had been marked in India ink. The experiment 
is illustrative of the difference between the erythema from 
thermal energy passing as it did in two hours, and the 
erythema from chemical energy, increasing after three hours, 
in the unprotected parts, going on to intense reaction, des- 
quamation and pigmentation. Solar erythema also begins 
some time after exposure. Likewise in therapeutic uses it 
is the late reaction which characterizes an expenditure of 



chemical light energy. It may appear in a few hours, a day 
or in 2 days time. When the skin is very thin, very 
vascular, this reaction appeal quickly, hack of the 

ear, over the mastoid region f<»r example. The author has 
rved it in that region 20 minutes after the exposure and 
of increasing severity from hours. 

Still more recent are the experiments of Freund. 

Experiments as to Penetrability of Ultra- Violet Fre- 
quencies, — Ffetind 1 endeavored to establish for himself 
I 1 I whether the ultra-violet frequencies penetrated the 
epidermis and reached the hnver layers of the skin T and | a I 
which part of the ultra-violet spectrum had this peculiar 

The experiments were undertaken in the photo-chemical 
laboratory of the Imperial Graphisehe Lehr u, Versucha- 
Anstalt, in Vienna, under the supervision of Prof* 
Eduard Valenta. The material used was ( 1 ) fresh epider- 
mis from burn blisters, (2) fmm the bullre of pemphigus 
vulgaris, and {3) fragments of epidermis from animals. 

Both of the first two were carefully removed with scis- 
KJTSj placed <>n glass plates, and preserved in the fluids with- 
drawn from the blisters by a small pipette, for the short 
distance from the sick room to the laboratory. The latter, 
like the two other preparations, were kept in a normal saline 
solution. A spectroscope with a grating was used, instead 
of the ordinary spectroscope which decomposes light into 
its constituent parts by meanfl of l glass prism, for, as has 
been shown, glass is not transparent to the ultra-violet fre- 

Previous experiments made by Strehel furnished quali- 
tative proof by the lighting up of the fluorescent screen of 
the power of the ultra-violet frequencies under given cir- 
cumstances to penetrate the skin, but only spectrographs 
examination of the penetrating light coultl determine defi- 
nitely just which constituents of the light possessed this 

'Radiotherapy: Fremiti, page 428. 


power. Hence the use of the spectroscope with a grating 
as was done by Bernard and Morgan in their experiments. 

The various membranes were spread carefully on one 
quartz plate and covered with another. Examination with 
a strong magnifying glass was then made showing that 
there were no gaps nor tears in the membranes. The quartz 
plates were then fastened in front of the opening of the 
"grating spectroscope." The spark light from a powerful 
Ruhmkorff coil, intensified by Leyden jars, was used ; the 
electrodes between which the spark passed were coated with 
an alloy of lead, zinc and cadmium (Eder's alloy). The 
spectrum of the light from this source was then photo- 
graphed, first with, then without, insertion of the prepara- 
tions. The opening was 0.2 mm. wide, and the tissues were 
exposed to the action of the light for 15 minutes. 

Under these conditions it was shown that absorption of 
the ultra-violet frequencies began at the cadmium line, 
X = 3,260 A, i.e., that this line under the given conditions 
is just recognizable on the film, while the light of the more 
refrangible rays no longer produces blackening, being, 
therefore, absorbed. There was no marked difference in the 
transparency of the three different preparations. 

From this experiment Ereund reached the following con- 
clusion : "In consequence of this, we may assume with cer- 
tainty that of the blue, violet and ultra-violet rays, those 
up to the wave length of the cadmium line, penetrate the 
epidermis. 1 ' 

Exj)criments were then made for the purpose of com- 
paring the behavior of dried epidermis with that of moist 
and fresh normal epidermis. Eor this purpose, films of 
almost colorless horn and of horn slightly colored yellow, 
0.5 and 0.56 mm. in thickness respectively were used. They 
were tested by examination under sunlight with the "grat- 
ing" spectroscope. The yellowish horn, with an opening of 
0.1 mm., and an exposure of 80 seconds allowed the light 
up to the Eraunhofer's line ( ), — 3,440 A to pass 
through; under the same conditions with the colorless horn 


tin- ultra-violet rays were effective Dp to Q z= ^ 3,287 A, 
These experiments showed that dead epidermis has on the 
whole die same absorptive p the living epidermis, 

but Hie permeability of colored, thai is, pigmented epidex 
was shown to be sensibly less than that of the former. 

Still more recently this subject has been studied by 
Bernard and Morgan in connection with their experiments 
on bacteria. 

This part of the investigation comprised their third 
series of experiments. These were made to determine what 
part of the energy of the spectrum was active in exciting 
reaction on the part of the tissues, and while si e, are 

not rfed as conclusive by the experimenters. 

The shaved skin of a rabbit, anaesthetized, to secure ab- 
solute quiet, was subjected to the spectrum, with the same 
spectroscopic arrangemenl as in their experiments upon 
bactertai and no effect whatever was produced after an 
exposure of 2] hours, with a current of 25 amperes. 
Guinea-pigs, whits rats, frogs, and even a human arm were 
similarly subjected to the same spectrum, but with abso- 
lutely no evidence whatever of tissue reaction. 

An additional experiment seemed to show that the 1 
exciting this reaction exist somewhere in the ultra-violet 
region. A rabbit shaven i^n both sides of its body was sub- 
jected to the action of the light from a 25-anipere electric 
arc passing through the water-circulating apparatus. Con- 
tact was made with the quartz disc on one side for 5 min- 
utes. Then the other side was exposed in the same fashion, 
>avc that a sheet of glass was inserted between the water- 
cooling apparatus and the skin. The second exposure lasted 
an hoar, and was made with a current of 25 amperes. On 
the following morning, on the side exposed to the rays 
through glass for an hour, lIj I it el v no effect had been pro- 
duced on the skin, while un the side exposed but 5 minutes 
through quartz and without the intervention of glass, there 
was a well marked redness. 

This, the author has < dearly substantiated in the thera- 


petitic uses of apparatus arranged with ( t ) glass plates or 
discs, (2) quartz discs, and also in experiments made upon 
culture plates, the bactericidal effect being active with the 
quartz, absent with the glass. The well-known transparency 
of quartz to the extremely short and high frequencies, ultra- 
violet, and their loss or absorption upon the interposition of 
glass, accounts for the results obtained both experimentally 
and therapeutically. 

All rays of the spectrum, save the greater part of the 
ultra-violet, readily penetrate glass, and any effect obtained 
with apparatus containing lenses or globes of glass is due to 
the more feeble penetration of a few of the frequencies on 
the extreme edge of the violet as it merges into the ultra- 
violet region. To obtain the maximum action of ultra- 
violet and blue violet frequencies is to secure the maximum 
result in the treatment of such pathologies as lupus vulgaris, 
as has been done by Finscn. 

It is then clearly proven that the frequencies which 
excite tissue reaction are to be found in the ultra-violet 
region, but it is not yet accurately determined in just what 
portion of the ultra-violet spectrum they are located. 

Chronic Lesions Due to the Action of Chemical Light 
Energy upon the Skin. — Chronic lesions of the skin are 
established by the chemical energy of light which manifest 
themselves (i ) by pigmentation, and (2) by vascular modi- 

Vascular Alterations Produced at the Level of the Skin 
by the Chronic Action of Chemical Light Energy. — Some 
months after the experiment upon his arm Finsen 1 observed 
no trace of the intense reaction which had taken place in the 
unprotected regions. One morning about 6 months after 
the experiment when at his toilet, upon rubbing his skin 
he observed that the part of the forearm which had been the 
seat of the photochemic erythema presented a much more 
marked redness than the parts which had been protected by 

'Journal of Physical Therapeutics. April, igoi. 



the glass plates. This difference finds its explanation m a 
persistent dilatation of the vessels and capillaries of the skin 
following upon the action of the light. 

In the anther's experience t Ik re has occurred a perma- 
nent and marked dilatation of all the capillary blood vessels 
of the inner and outer aspect of both kgs, but especial!} of 
the inner, in the person of an invalid lady, from prolon g ed 
and constant exposure to the chemical light energy from a 
hard-coal fire. By reason of her profound anannia and im- 
perfect Circulation she w.i very near the fire 
for hours at a time, and was in the habit of raising her skirts 
to prevent their being scorched. In consequence there is 
not only the dilatation, hut also marked pigmentation* and 
after a lapse of from 4 to 5 years it is as evident as at first. 
The action of thermal stimuli at this time causes a very 
prompt reaction 50 marked as to outline the anastomoses of 
the superficial capillary vessels. 

Fin ii established the dilatation of the capillaries in his 
experiments upon the tail of the tadpole, while Leredde and 
Pan trier showed it by their examination of sections of the 
skin acted upon by light energy. 

Finsen and Moeller proved by experiment a peculiarity 
of light reaction corresponding precisely to that observed 
by Freund with Roentgen ray reaction, viz., that skin which 
has been exposed to tin- influence of powerful chemical light 
v, blue- violet and ultra-violet frequencies, retains for a 
long time, months an after the first light erythema 

has disappeared, a peculiar predisposition to react with re- 
markable promptness to mechanical, chemical and thermal 
stimuli, and also to internal influences, psychical stimulus, 
for example. This reaction is evidenced by a very quick 
reddening of the part. 

The more active cutaneous circulation established by light 
is a condition of better function for the skin. 

This is true of the physiological action of ordinary sun- 
light upon the cutaneous covering. In this connection, how- 
ever, it is the action of concentrated light upon the skin. 


It is no longer an acute phenomenon of a common inflam- 
mation but a chronic phenomenon of some sort, producing 
itself after long periods of time. But other tissues are in- 
fluenced by this action. It was observed by Bcrthold 1 that 
the nails, the beard and the hair grew more rapidly in sum- 
mer than in winter. Finsen 2 inquired of the coiffeurs, and 
according to them it is a current observation that it is not 
necessary to shave so often in winter as in summer. Tt has 
been observed in Finsen's clinic that Ixrth patients and nurses 
acquired a thicker growth of hair on those parts repeatedly 
exposed, and for long periods to the powerful electric arc 
energy. It has also been proven, and it only further illus- 
trates the same phenomena, that amphibia and fishes whose 
limbs have been broken off grow again more rapidly in the 
light than in the dark. 

The explanation lies in the fact that in the summer, by 
reason of the abundance of light, the skin is better nourished 
than in the winter; with the amphibians and fishes there are 
more active circulatory conditions in light than in darkness. 

This action on the cutaneous circulation not only pro- 
duces a temporary hyperemia, but, as has been indicated, 
a lasting one, a condition which unquestionably influences 
favorably the diseased area, subjected to the action of the 
chemical frequencies. In all diseased conditions, where the 
vital processes are below normal, whether accompanied by 
the presence of a germ or not, as in tuberculosis, the best 
result is to be obtained by securing a hypenemic condition 
of the tissues. To this end, every means is tried to stimulate 
circulation and to produce the hyperemia necessary to estab- 
lish restoration to normal conditions as in a tuberculous 
lung, joint, gland or skin lesion, or to establish healing, as, 
for example, in a varicose or tubercular ulcer. 

Chemical stimulants in the form of lotions, ointments, 
even injections are used ; the aid of electricity is invoked 
either to produce the characteristic action of the current, or 

"Mueller's Arch, fiir Amt. unci Physiol., 1850. p. 15S 
'Mitt, aus Finscn's mod. Ly>.. V<»1. 1.. p 118. 



hv means of it to deposit within the tissues the salt of an 
oxidizable metal, l»\ the action of light, the same effect 
is produced, an effect which is deep seated and lasting. 
The n for tins hypenemia is. if possible, more neces- 

sary in tubercular affections than in other pathologies. It 
is by . cply penetrating action of light that 

favorable results ensue. 

Applications of typical chemical stimuli are very super- 
ficial in their effect. The Ear-reaching and permanent effects 
obtained by the light vibrations .ire comparable to the ef- 
fects produced by the deposition of salts of oxidizable metals 
at tin- anode or drugs in solution or suspension^ both ana- 
phoric and cataphoric medication. By the action of the 
salts of oxidizable metals, far-reaching and lasting results 
are obtained. 

It is believed that the chemical products of the bacteria 
are accumulated by the action of the light, a condition which 
is unfavorable to their development, As the chemical fre- 
quencies of light, especially the ultra-violet rates, have the 
r, by reason of their short wave length and very high 
frequency, to agitate bacteria, shake them up as it were, a 
physical condition inimical to their vitality, they umst by this 
action be deprived of their oxygen. Such a deprivation 
would mean an accumulation of their chemical products. 
Meanwhile the same action which results disastrously to 
them gives an impetus to the norma] oxygenating power of 

I I:., blood. 

There is no radical difference in the mode of action ol 
the different means employed for the production of a physio 
i irritation. Whatever their nature, they follow a 
universal law, and tin result of their use is both inhibitory 
and constructive. Bacteria are inhibited, morbid growths 
due to them resolvedi metabolic i ns and their skin 

expressions overcome, and all the while the beneficent action 
of light upon the organism as a who:, n tending to 

an elevation to the normal standard. 

The formation of connective and scar tissue depends 


always, whatever its locality or however formed, upon a 
preceding hyperemia. 

It has been stated by Lang 1 that the pressure employed 
by means of compressors was the curative factor, and he is 
responsible for the statement that he has cured lupus by 
pressure alone. This has not only not l>een substantiated by 
any other observer, but it has been proved beyond per- 
adventtire that it is the penetrating light, chemically active, 
which excites tissue reaction and which cures lupus. 

But side by side with the vascular modifications, another 
phenomenon occurs from the prolonged action of chemical 
light energy upon the skin, viz., the production of pigment. 
This may be regarded as a process of defence or adaptation. 
Beyond question it is the act of defence on the part of the 
skin in relation to the chemical rays. It will be remem- 
bered in considering the role of light in the pigmentation 
of animals that the deepest part of their coats is always the 
dorsal surface, which is the one most exposed to light. Of 
equal interest and pertinence in this connection are the ex- 
periments of Packard and Vire on the cavernous species of 
animals. (See Action of Light on Animal Organisms; the 
Influence of Light on Pigmentation.) In man the pigment 
production appears to be the same in all parts of the body 
exposed to light. The action is not due to the wind, to sea- 
air, or exposure to inclemencies of weather, but is one of 
chronic alteration involving the pigment cells due to chemical 
light energy. As is commonly observed, it follows sun- 
burn. Both Finsen and Widmark noted a consecutive pig- 
mentation in their experiments. Pigmentation left after 
exposure to strong light comes from the accumulation of 
hemosiderin in the interstices of the tissues. 

The Role of Pigmentation as a Process of Defence. — 
This is established in part by the more active cutaneous 
circulation consecutive to the ih>t chemical light ervthema. 

'WiriKT (IiTnintnlnir. f itsclNcli.i ft ami IV. Intirnat. (.'• Micros 
f. Derniatnlogie and Sypli., Aug. 2, i<KK). Cnnipt. rend., p. 171, t|tintc<l 
by Frcuncl. 

- n J 


The red medium, the blood, absorbs the violet and ultra- 

violet fret i 


other tis 


more man any otner tissue. jiy n 
of the stimulus thus Imparted there is mcreas 

power, Le-, the red blood corpus ire richly 

stored with oxygen. This doubtless serves as an appre- 
ciable agent of protection. By reason <>f the histological 
changes, i.e. an (edematous, thickened, spongy epidej 
the penetration of the chemical frequencies of short length 
is prevented. The practical application <«f this should no! 
he lost sight of in therapeutic applications, Lew, not to re- 
peal an exposure until the reaction has sufficiently subsided: 
for an epidermis in th lition cannot be transparent to 

light, that is, permit rption. 

It is the pigmentation, however, which plays the mO£t 
important part ill Ihe process ii - It defence. Finsen and 
Gtard, in France, have both voiced the theory. No b 
illustration of it is to be found than in the dark coloring of 
the peoples i i the tropics. 

Pigmentation as One of the Factors of Natural Selec- 
tion. Perhaps there is some evidence of this. It was 
studied h\ Bohn, 1 who, in considering the struggle that living 
beings sustain among themselves and against the diverse 
agents of the external world, declares that there results 
From the ensemble of these phenomena an impression of 
harmony. Struck by the role played by pigment, liohn ad- 
mitted by the side of physical and chemical harmonies, 
which only reveal themselves after much analysis of biol 
eal phenomena or nut at all. pigmentary harmonies. 

• I ants have been struck by these harmonies of colors, 
and to the minds of Wallace. Darwin. Poulton, Giard, they 
play an important part in the affinities of beings among 
themselves and in their relations with the external media, 
The theor) is known under the name of mimctism. 

Pigmentation as a Process of Adaptation. — It is prob- 
able that pigmentation may be regarded quite as much a 

devolution du Pigment, Joe cit. 


process of adaptation as a process of defence. But even so 
the two functions run imperceptibly the one into the other. 

Lcredde and Pautrier are of the opinion that in pig- 
mentation in the animal kingdom and upon the human skin 
the process may be one of adaptation by which the pigment 
might utilize the chemical energy of the spectrum, trans- 
forming it into energy, which in turn may be utilized by the 
organism in a form of which nothing is known. They 
state in this connection an admitted fact, viz., that the 
sobriety of the races of the tropics is well known, and that 
the sum total of work of which they are capable is entirely 
disproportionate to their apparently insufficient ration. The 
explanation of the difference in alimentary regime l>et\vcen 
the people of the north and the people of the south, which 
is always offered, and so far as is known, is the correct one, 
is that because of the difference of temperature the former 
require more food to resist the cold than the latter. These 
authors raise the question as to the light energy, whether it 
may not also play a part in these phenomena. The author 
would say that because no such relation is known and proven, 
the possibility of its truth is not precluded. All about us 
in nature is a wealth of unanalysed truth. In so perfect and 
stupendous an organization as the universe, there is an ex- 
planation for every observed fact. To the author's mind it 
seems more than possible that when biological phenomena 
are more fully analyzed and understood, there will be found 
a correlation of the first order between the radiant energy 
of the sun and all the phenomena of life. Reverting, how- 
ever, to known facts in the wealth of observed phenomena to 
the minutest detail of the action of light energy upon the 
skin as studied by Widmark, Finsen, l ; reund, Bernard and 
Morgan and Lcredde and Pautrier, there is builded a scien- 
tific foundation upon which future biologists may hope to 
rear a superstructure of as carefully analyzed biological 
phenomena, which in its turn will tend to elucidate the rela- 
tion of life to light. 

The Action of Light Energy upon the Blood. — As an 


III !•. N I- l 

evidence of the relation between tight and life is the fact 
that certain constituents nf annual tissues permit of tb 

of light. This transparency is of J value in 

the use of light as a diagnostic agent, a method much in use 
before the discovery of the Roentgen ray. 

Tissues differ in regard to their transparency to light. 
It is a matter of their structural density and the chen 
nature of the layer, but especially the uniformity of the tissue, 
both as regards the nature of Its matter and its density. AJ1 
of the substances nf the living organism are not equally 
{parent to the different frequencies nr colors nf the 
spectrum. For example, tile blond transmits the red fre- 
quencies hut absorbs the mure refrangible frequencies. 
Freurtd's experiment showed that in the living frog's web, 
the blond absorbs all the light from Fraunhofer's line H, 
or wave length 3*964 Angstroms. 

In order to have an actual picture of the transparency of 
the living I issue to the red frequencies, let the reader place 
the hand over a source of light, or place a small incandescent 
lamp within the ninuth. Light is used in this way as a test 
for hydrocele. In the transmission of the longer and slower 
Frequencies in all these instances, the fact that it penetrates 
the skin is shown. A diamond ring may be made to Sparkle 

when covered with a finger, for example, which is illumi- 
nated from above, and even when the finger is covered with 
white or chamois leather. This was first shown by Des- 
saignes. (u-hhard 1 imbedded a hand so completely in plaster 
of Paris, in the hollow of which he had placed a photographic 
dial only the back of it was exposed to the luminous 
energy of an electric arc fur 20 minutes. The plate was re 
moved to a dart room and developed. It was blackened, 
and the outlines of the hand and fingers were distinctly 
seen. This demonstrates that no! only light, but light chemi- 

Callj active passed through the hand. 

From the experiments nf (iadneff- the nature of the 

i>u Hcilkrafi des Lkhtcs, Leipzig, [808, p. mi. 
'Quoted by Boubnoff, Arch. f. Hyg., Vol. X.. p, .u5- 


penetrating energy is shown. He filled small tubes with 
chloride of silver, sealed them hermetically, and then by the 
aid of a trocar carried them under the skin of living dogs 
and cats. Some of the animals were placed in captivity in 
darkness, while others were allowed to run free exposed for 
some time to the action of the sunlight. In the latter, the 
chloride of silver was blackened, in the former no change 
had taken place. Finsen's experiment on his wife's 
ears not only demonstrates the passage of chemically active 
light, but proves that the blood interferes with its passage 
to a very great extent. 

Still another experimenter, Darbois 1 showed that a 
piece of photographic paper introduced into the mouth under 
the skin of the check between two watch glasses was 
blackened after one minute's exposure to the light energy 
from an electric arc used in connection with a Finscn con- 
centrator directed to the outside of the cheek. 

Solucha 2 filled tubes with strips of silver-bromide-gela- 
tin inserting them under the skin of dogs and sewing up 
the incisions made to receive them. He used a projection 
apparatus at 50 to 65 volts pressure and from 10 to 20 
amperes current strength. The bromide of silver was seen 
to be decomposed after one minute; When the tubes were 
carried down deep into the glutei muscles on the other hand, 
the sensitive paper was not acted upon, showing that the 
light did not penetrate so deeply. The decomposition soon 
set in when similar tubes were placed behind the car or 
inside the cheek of patients in the first instance after half a 
minute, in the latter after two minutes, while when placed be- 
hind the forearm or in the fist the sensitive paper was un- 
changed after 15 minutes. By an increased light inten- 
sity, say 25 amperes at 1 10 volts pressure, the entire body 
can be penetrated, for under such conditions the sensitized 
gelatin film was chemically altered even when placed upon 

'P. Parbois. Tniiu-meiit du Lupus Vulgaire, Those de Paris. 
1901, p. 80. 

"Quoted by Fivund. 



tin- opposite side of the body from the pan exposed to the 

light. Solueha for example placed it at the back of the neck, 
when exposing the throat or at the right suk- of the bodj 
when the light came from the left. 

As further proof of the pmetrating power of even chemi- 
cally active light energy, are the experiments of Kinuv 1 
FqC a source of light energy the sun's rays were Utilized and 
the light passed through the thorax to the sensitive him 
placed upon the patient's hack. 

Finsen observed distinct weakening of a bacteria culture 
w hich he placed hack of the ear of a white rabbit and through 
which lie passed concentrated sunlight. He also showed 
thai the light passed through the compressed lobe of a 
human ear could be broken up dearly into all the colon of 
the spectrum. St rebel* utilized Lbe fluorescent property of 
ultra-violet energy to prove the penetrability of the human 
skin in the following manner: A piece of skin freed from 
all fat tissue was fixed between small quartz plates; all of 
the colored frequencies of light energy were excluded and 
it was exposed to ultra-violet energy, produced by the induc- 
tion sparks from zinc and aluminum electrodes. The dis- 
tance between the skin and the spark was [40 cm. Upon 
placing a fluorescent screen behind the skin it showed that 
a human ear compressed bet ween two quartz plates absorbed 
isolated ultra-violet frequencies completely. 

That there is a penetration then not only of energy which 
a fleets the visual organs but of the energy which is chemi- 
cally active through animal tissue, is thus very compli 
demonstrated. The penetration may take place through tis- 
sues of considerable thickness under certain conditions. 
1 hi- ultra-violet frequencies alone barely penetrate the 
epidermis, even when applied in a concentrated form but 
w lirti combined with the blue indigo and violet, the complex 
of frequencies is much more penetrating, being absorbed by 
the first thick layers of the blood vessels; while the red and 

'New York Medical Record 
h-ni !u Med, Wnclienschrift, 1901, Nos. 5 and 6. 


infra-red permeate the cutis and pass into the deeper tissues. 
The tissues of the tody to a considerable depth are diapha- 
nous to the red frequencies as is shown by their transmitting 
effect. With a miniature incandescent lamp of small candle- 
power it is possible to transillumine the pelvic tissues to 
within two inches of the umbilicus in a subject of ordinary 
avoirdupois and thickness of abdominal fat. That these 
longer and more deeply penetrating waves are subjected to 
some modification of their motion, a temporary arrest, as 
suggested by St rebel 1 , seems possible. Their wave length 
is entirely out of proportion to the size of molecular struc- 
ture and it does not seem possible that the latter would in- 
sure their temporary arrest, for when a wave strikes an 
obstacle that is much smaller than the wave length, the wave 
gets by the obstacle without much difficulty and in that event 
little or no energy is expended, therefore little or no work 
is done. 

From this physical law it would appear that in so fir as 
the structural nature of the tissues permits of the transmis- 
sion' of the energy of red light, or the long and slo\v fre- 
quencies there is little or no energy expended or work done 
in them. On the other hand in their action upon the deeper 
and more translucent structures the ultimate energy would 
only heat, as it could not penetrate so far without absorp- 
tion. The disruption of molecules and consequent effect 
upon molecular structure is more likely to occur the higher 
the frequency of the oscillating light corpuscles. 

Light is converted into heat waves and perhaps into long 
electrical waves. The energy of the spectrum is transformed 
into other forces, the forces which arc inherent, viz.. 
electric, osmotic and the vibrational action of molecules or 
other mechanical energies. A direct action upon the chemi- 
cal processes and stimulation of the functions of the tissues 
and protoplasm is established reflexly by exposure to light 
energy. Light acts as light by its chemical activities alone. 

'Die bishi-rigcn Leistungen dcr Lichttherapie. Berliner Klinik, 
February, 190.2. 

-7 n 

ih.Hi ENERGY. 

and the primary action is upon the blood, by which its 
oxygenating power is increased* 

If in consequence of the exposure of large body superfi- 
cies to the influence of strong tight the accumulation of 
hemosiderin in the interstices of the tissues, that is, the 
giving off "i blood coloring matter takes place to a very 
great extent, a certain impoverishment of the elements of the 
blood and the coloring matter may ensue. As a result the 
organism may be Stimulated to increased functional activity 
mpensate for this change. This theory advanced by 
Ldwenthal 1 offers a rational explanation of certain meta- 
bolic changes which take place under the influence of light 

The influence which light energy exercises upon the 
U od and capillary systems in living organisms is one of 
great importance. By its action blood vessels undeq 
change in form, as has been fully demonstrated b] 
tensive experimental work. The action Upon the blood 
stream itself, however, i^ one of absorption and the absorp- 
tion of energy means the impartation of a stimulus to the 
functioning parts or whole of the living organism. In this 
instance the Stimulus is imparted to the blood corpuscle and 
.the direct action of the energy absorbed appears to be upon 
tlu storer of oxygen or the red blood corpuscle. By the in- 
crease of oscillating movement or swing of the corpuscle 
there must be an increased energy of action according to 
every physical law. li is the penetrant chemical frequencies 
the blue, indigo violet and ultra-violet, that thus act upon the 
red media. From accumulated experimental data and clini- 
cal observation, as Well as from a study of the physical laws 
of light and their correlation to the living organism, is found 
constant proof of this fad. 

Spectrum of Haemoglobin. — A glance at the constitution 
of the red blood corpuscle and at the spectrum of haemoglo- 
bin cannot fail to be n\ interest and value in the study of the 
action of light energy upon the blood. 

'Deutsche Mril Xtitniig, 1899, No. 72, 


Human red blood corpuscles singly are biconcave circu- 
lar discs of a yellow color with a slight tinge of green ; they 
seem to be devoid of an envelope, are certainly non-nu- 
cleated and appear to l>e homogeneous throughout. Kach 
corpuscle consists (i) of a framework, an exceedingly pale, 
transparent soft protoplasm — the stroma ; and ( 2 ) the pig- 
ment or haemoglobin, which impregnates the stroma much as 
fluid passes into and is retained in the interstices of a 
sponge. Haemoglobin possesses some remarkable properties. 
Although it is a crystalloid body it diffuses with difficulty 
through an animal membrane, owing to the large size of its 
molecule. (3) It readily combines with oxygen to form 
an unstable and loose chemical compound, oxy-haemoglobin. 
(4) This oxygen it gives up readily to the tissues or other 
deoxidizing agents. (5) Its composition is very complex, 
for, in addition to the ordinary elements present, in proteids, 
it contains a remarkable amount of iron (0.4 per cent.). 

Graffenberger 1 maintains that the mass of hemoglobin 
contained in the red blood corpuscle is lessened in the dark 
and that from a prolonged stay in the dark there is a dimi- 
nution in the total quantity of the blood. 

Marti 2 , in his experiments upon rats, established the fact 
that the deprivation of light lessens the number of red blood 
corpuscles, and to a less extent the amount of hemoglobin, 
while from exposure to strong light continuously, the forma- 
tion of erythrocytes and also of hemoglobin was stimulated. 
Haemoglobin is then active in the absorption of these chemi- 
cal frequencies and in the relatively large size of its mole- 
cules is to be found a physical condition favorable to the 
physical action of these periods of oscillating light corpus- 

The stimulation imparted results in an increased activity 
of oxygen absorption and the formation of oxyhemoglo- 
bin. A study of the spectra of oxy-hemoglobin and mcta- 
haemoglobin, both absorption and flame, should be of the 

"Pfliigcr's Archives. iSgj, Vol. LIU. p. 238. 
*Verh. d. Congress f. Inncre Mid.. 1897. 



same if not greater interest to the therapeutist than it is to 
the physiologist and pathologist. A glance at the spectrum 
of haemoglobin demonstrates that it is no exception to the 
rule. The general coloring" in the case of well-oxidized 
arterial red-btood corpuscles i t; with venous b 

a darker red A single corpuscle shows a yellow coloring 
with a slight tinge of gt { 

Thus in the green, yellow and red coloring is to be 
found the evidence of the energy of radiation of the emit 
ting or, in this instance, the fluorescent tissues of the body, 
all of them below the longest wave length of the vi 
chemical frequencies, or the blue. 

Flame Spectra. — In the ashes of almost all organs are 
to be found the bands, which indicate the presence of potas- 
sium and sodium. 

Absorption Spectra. — If a solution of blood be placed 
between the slit of the spectroscope and a source of light, 
all the rays erf colored light do not pass through it— 
are absorbed ; many yellow frequencies or rays are ab- 
sorbed hy blood, hence that part of the spectrum appears 
dark to the observer. This should hear a relation to the 
presence of sodium in the blood, and its constant pres- 
to the spectra of all sources of light. On account 
of this absorption such a spectrum is called an absorption 

If sunlight be allowed to fall upon the slit, the spectrum 
shows a large number of lines, FrannhoftVs lines, which 
occupy definite positions in the spectrum. These lines 
are indicated by the letters A, II, C, D, E, F f G, H. II,, etc., 
as shown in Fig. 9. 1 

Qxy-haemoglobin. — Oxyhemoglobin behaves as a very 
weak acid, and occurs to the extent of 86,78 to 04.30' 
any human red corpuscles. It is formed very readily when- 
ever haemoglobin comes in contact with the oxygen or 
atmospheric air, 1 txy-haemoglobin is a very weak chemical 
compound, and is slightly less soluble than haemoglobin; its 

*Scc plate facing page 253. 


spectrum shows in the yellow and the green two dark ab- 
sorption bands. 1 It occurs in the blood vessels circulating 
in arteries and capillaries, as can be shown by the spec- 
troscopic examination of the ear of a rabbit, of the prepuce 
and the web of the fingers. 2 

Spectrum of Oxy-Hsemoglobin. — In the spectrum of a 
dilute solution of haemoglobin crystals of arterial blood, part 
of the red and violet frequencies are absorbed, but two well- 
marked absorption bands exist between D and E. The 
line nearest D, i.e., next the red end of the spectrum, some- 
times designated by the letter a, is narrow, sharply defined, 
and black at its centre, and in its wave length corresponds 
to wave length 579. 

The other absorption band near E, conveniently desig- 
nated by b, is broader, not so dark, and its edges are less 
sharply defined. Its centre corresponds to wave length 


In very dilute solutions the band is the only one visible. 
In strong solutions the two bands fuse, but are again made 
visible as two on dilution of the blood. 

The spectrum, therefore, necessarily varies with the 
strength of the solution. With a \'?< solution all the spec- 
trum disappears with the exception of the extreme red, and 
as the dilution continues, the orange, green, blue, indigo 
and violet are successively seen. With 65% solution of 
HbCX, there is only one absorption band. 

Spectrum of Reduced Haemoglobin. — By adding to a 
solution of haemoglobin reducing substances — e.g.. ammo- 
nium sulphide, iron filings, Stokes's fluid (tartaric acid, inm 
protosulphate, and excess of ammonia) — the two absorp- 
tion bands of the spectrum disappear, and reduced haemo- 
globin (gas free) with one absorption band is formed. 
The color changes from a bright red t<> a purplish or claret 
tint. The two bands are reproduced by shaking the reduced 
haemoglobin with air, whereby HbO J is again formed. So- 

'Landois and Stirling, p. j6. 



ttltftOfia of nxv-haejTioglotain are readily distinguished by their 
scarlet color from the purplish lint of reduced haemoglobin 

According to Hermann, the absorption hand of lib is 
not a Single band, there being in addition a very narrow- 
band toward the red end of the spectrum, but separate 
from the chief absorption band by a small interval. 

McthcTmopIobin is a more stable crystalline compound 
than oxydiremoglobin, ft contains the same amour i 
O as HbO Al but in a different chemical union, while the 

is more firmly united with it. It shows four absorption 
bands like haematin in acid solution of which that between 
C and D is distinct: the second is very indistinct, while the 
third and fourth readily fuse, so that these last two bands are 
only seen with Rood apparatus. 1 

Frcund undertook to determine to what extent the more 
refrangible rays were absorbed by the blood. To this end 
a few drops of blood from a finger tip were squeezed OH 
to a quartz film, which was surrounded by a run of paper 
0.17 mm. wide, and covered with another quartz film. The 
blood completely filled this space of 0.17 mm. This layer 
1i \ vrd a uniformly red color without any light space. 

1 pon examination with a little pocket spectroscope, the 
usual absorption spectrum of blood was seen, with the char- 
acteristic absorption band between the Frauuhofer lines — 
D and E in the greenish yellow. By the aid of a small 

spectroscope and using sunlight, the spectrum was 
photographed. With an exposure of 5 minutes, the image 
of what had been seen was reproduced showing that absorp- 
tion began at F } G, and from that poind onward, in the 
direction of the ultra-violet, practically no action on the 
photographic plate was discernible. 

A farther experiment was made in order to discover the 
behavior of living fresh epidermis, beneath which the blood 
is circulating. A frog was put under curari, then two toes 
of a hind foot were fastened v\ itb pegs along the edges of 

"LajHfou and Stirling, 


a triangular hole cut in a sheet of cork, in such a manner 
that the web of the foot was fixed in front of the opening 
of the slit of the spectroscope through which solar light was 
allowed to fall. The opening was 0.15 mm., the exposure, 
5 minutes. Under these conditions the line H (A 3,964 A) 
was absorbed. It is interesting to know that so many of 
the frequencies from the more refrangible part of the 
spectrum should still be able to pass through when the 
thickness of the membrane and the quantity of the blood 
contained in it is considered. It follows, therefore, that a 
considerable portion of the ultra-violet frequencies emitted 
by various sources of light pierce the epidermis, and are 
able to reach the lower layers of the skin. So far as is at 
present known Freund finds that these penetrant fre- 
quencies of the ultra-violet spectrum, roughly speaking con- 
stitute a third part of the ultra-violet spectrum as at pres- 
ent known. There are several different factors governing 
these results, the intensity of the source of light, the dura- 
tion of the action, and the thickness of the exposed layer. 
Under more suitable conditions, such as obtain, for ex- 
ample, in the treatment of lupus patches and nodules by 
Finsen's method, a more profound penetration of the epi- 
dermis by these very short and high frequencies is possible. 
It is, therefore, evident that blood absorbs light to a 
very great extent, and in a somewhat peculiar manner. 
This is show r n by the characteristic absorption spectra of 
greenish yellow obtained by Iloppe Sevier, and in blue vio- 
let by d'Arsonval. It is further emphasized by the experi- 
ments of Freund made to determine the degree of pene- 
tration of the ultra-violet frequencies. The classic ex- 
periments of Finsen evidence additionally the absorptive 
power of the blood for blue violet light energy. lie placed 
a piece of sensitized (aristo) paper back of the lobe of his 
wife's ear. The concentrated beam of light from one of his 
arcs was then directed upon it, securing the passage of the 
more chemically active frequencies, or the blue-violet and 
ultra-violet. Nothing was done in the first experiment to 



\\ the circulation. After an exposure of 5 minutes 
tin-re was no action whatever up«»n the paper, i.e., it was not 
blackened. • U] ittg the ear between 2 glass 

plates until it appeared pale ami bloodless, a second expos- 
"yre was made for 20 seconds, resulting In a blackening of 
the paper. This demonstrates very clearly the fact that the 
blood to a very considerable extent prevents the penetration 
of the chemically active frequencies into the I while 

the absorption spectrum of oxy-haemoglobin indicates that 
the blood absorbs them. From the constitution and the ab- 
sorption spectrum of oxy-hamogtobin it is clear that the 
haemoglobin is an active absorbent of light It has 

been pointed out that the absorption spectrum of oxy-ha?nm- 
globtn IS different from that of met I: bin, 

It has been shown by Quincke 1 that hsemoglobin gi 
off its oxygen more quickly in the light than in the dark. 
In darkness the oxy-hiemoglohin band in the spectrum 
vanishes. This proves that tight energy increases the 
dizing power of the blood, and proportionately the processes 
of oxidation in the living organism, 

Absorption of light (see chapter on Fluorescence) is 
connected with phosphorescence ami fluorescence Fluores- 
cent bodies exhibit corresponding absorption~spectra, and, 
as they absorb the ultra-violet frequencies more or less com- 
pletely, they all fluoresce in this region of the spectrum. 

The blood and the lymph serum are fluorescent bodi 
and as such are amenable to the same physical laws as other 
fluorescent substances. Their fluorescent property indi- 
cates ilk absorption by them of the higher and more re- 
frangible frequencies blue, indigo, violet* and ultra-violet. 
Spectroscopic analysis of rays emitted by fluorescent sub- 
Stances has shown that in them the blue and all frequencies 
above it are suppressed. Therefore the light so filtered 
ceases to excite fluorescence in any other substances exhibit- 
ing the same pTOpefti 

'Piluger's Archives, 1894, Vol. LV11., p. 134. 


The question of the frequencies which excite the 
fluorescence of the blood, or for that matter, any tissue of 
the living organism which is naturally fluorescent, is settled 
by this physical law. It is further substantiated by experi- 
mental data which show conclusively that these penetrant 
chemical frequencies are the frequencies which are absorbed 
by the blood. 

The action of the light energy then, especially the pene- 
trant frequencies effective chemically upon the blood, is 
very clear of comprehension. In the ability of the blood 
and other tissues of the living organism to function as a 
transformer under the influence of the more intensely 
chemical frequencies or rays of the greatest refrangibility 
of light is to be found the rationale of its action, both in 
health and in disease. There is doubtless an equally scien- 
tific explanation of the action of the frequencies below the 
blue, but it yet remains to be made. One thing seems cer- 
tain that light produced within the body by means of drugs 
having fluorescent properties cannot, according to physical 
laws, have any effect upon the blood or other naturally 
fluorescent tissues of the body, if the frequency so produced 
is of lower order than the blue. 

In discussing the action on bacteria and therapy of 
fluorescent substances under the action of light, it is pointed 
out that the results obtained by exposure of fluorescent 
substances in solutions, or when applied to superficial sur- 
faces, cosin, for example, to light energy of high frequency, 
ultra-violet, the effect produced is due to the act of fluores- 
cent stimulation, just as it is with chlorophyll. This stimu- 
lation when once established is a continuing factor both in 
normal and a wide range of abnormal conditions, and the 
stimulation imparted to the blood by the action of light 
under physiological conditions is the same. It lasts for 
varying periods of time within physiological limits, but the 
maintenance of normal fluorescent properties of blood and 
fluorescent tissues must depend upon ( i ) frequent re- 
newals of the stimulation by exposure of the body in part or 



altogether to the action of sunlight, and (2) upoa the ab- 
sence of pathological conditions which interfere with the 
ability of the norma! fluorescent tissues of the body to func- 
tion as transformers of the frequencies from the blue on up 
into the ultra-vinlri region. The Plasmodium malaria is 1 
notable instance of a parasite which destroys the normal 
condition of fluorescence. 

But it does not seem unreasonable to believe that in a 
modification of the blood, such as is induced by the ]>r< 
Of a parasite as b malaria, of a toxin or potsod as m syphilis 
<r sepsis, of a bacillus as in tuberculosis, nr as the imp 
ishmeftt of anaemia both the rate and volume of atomic mo- 
tion must be altered. There may be a great deficiency in 
oxygen, iron, in the saline constituents, sodium, potassium, 
ammonium, and calcium, which must mean an inability on 
the part of the blood to fix the energy transmitted to it. that 
is, to absorb energy of radiation at the degree which permits 
tlir fluorescent condition normal to it under physiological 
conditions. When tin- departure from the normal is not too 
great, in the conditions mentioned, an expenditure of light 
energy if sufficiently localized and concentrated, as in a 
cabinet For general conditions, and by strict localization ant! 
compression in special lesions, should result in physiological 
fluorescent stimulation. This stimulation to the oscillating 
swing of the atoms cannot fail of response. 

Red blond corpuscles are diminished in size by septic 
fever, inanition, morphia, increased bodily temperature and 
CO s , but they are increased by O, by cold, quinine, etc. 
They are also diminished, at most one-half, by hemorrl; 
and also undergo a physiological diminution as a result of 
menstruation. Under ordinary physiological conditions this 
is a moderate loss and ilicy 10 replaced within 2$ 
days. When the loss is excessive the period of replacement 
may extend over 5 weeks with the result of lowering all 
the vital | ls in menorrhagias and metrorrhagias. 

This diminution of red blood corpuscles, with lowering 
Of the \ ; ta! processes, is more or less continuous. 


The size of the red blood corpuscle is also diminished in 
acute fevers. In certain forms of anaemia there has been 
found (Hayem) considerable variation in the size of the red 
blood corpuscles ; in chronic anaemias the mean diameter of 
the corpuscle is always less than normal. There is more- 
over a persistent alteration in the volume, coloring power and 
consistence of the corpuscles, consequently a want of accord 
between the number of the corpuscles and their coloring 
power, i.e., the amount of haemoglobin which they contain. 
In pernicious anaemia, in which the continued decrease in the 
red blood corpuscles may ultimately produce death, there 
is a severe affection of the blood-forming apparatus. 1 The 
corpuscles assume many abnormal and bizarre forms, often 
being oval or tailed, irregularly shaped and sometimes very 
pale; while numerous cells containing blood corpuscles are 
found in the marrow of the bone. In this disease, although 
the red blood corpuscles are diminished in number, some 
may be larger and contain more haemoglobin than normal 
corpuscles. In chronic poisoning by lead or miasmata and 
also by the poison of syphilis, the red corpuscles are like- 
wise diminished. 

The size of the reel blood corpuscle also varies in health 
and disease and dwarf corpuscles or microcytcs are regarded 
as young forms and occur plentifully in all forms of anaemia. 
On the other hand "giant" blood corpuscles or macrocytcs are 
constant in pernicious anaemia, and sometimes in leukaemia, 
chlorosis and liver cirrhosis. They also appear in abnormal 
forms after severe burns while a disintegration of the ( orpus- 
cle has been observed in various diseases, as in severe 
malarial fevers. 

These physiological facts concerning ( I ") the normal 
condition and function of the red blood corpuscle as the 
oxygen storer of the blood, and (2) its condition in disease. 
when taken in connection with the physical effects and 
physiological action of light s«*rve to illuminate the intimate 

'I^indois and Stirling. 



tionship b etw een animal life and radiant energy and to 
emphasize not Only the fact that continued existence is 
dependent upon it but the physical reasons for the same. 

Light Energy in Relation to the Menstrual Function and 
Bearing upon the Bl rxning Process. — According to 

Kulcnhnrg it is a fact that women of the far north arc very 
much more predisposed to amenorrlHea and during the long 
winter night menstruation is even completely suppressed, 1 
white according to Holmgren and Gyllenkrentz- the oxy- 
bsemoglobiti hand in the blood of these sul wed 

signs of extension at the close of the long Arctic night. 

Light Energy in Relation to Metabolism. — In our study 
of the action of light energy upon animal organisms it was 
found that after an initial decline there was an increase in 
weight of the animals exposed to light as against those kept 
in darkness and that also tissue change went on more rapidly 
under the influence of light. This action may he explained 
by a stimulation of the nervous system, which in its reaction 
stimulates other vital functions, or it may he a direct action 
upon the blood stream itself. Of the fact that certain modi- 
fications in the tissue change in both men and animals take 
place under the influence of light energy, there is no ques- 
tion. This action must he twofold, i.e., Upon the blood 
directlj and indirectly through the nerve system. 

There are certain observations based upon experimental 
work which seem to Eavor Hie theory of a stimulating action 
upon the nervous system. Quincke 1 demonstrated hy his 
experiments that various tissue cells, pus. blood, muscle, kid- 
neys, fiver, etc., absorbed more oxygen in the light than in 
the 'lark So long as they are not quite dead severed n 
ties and nerves according to Moleschott and Fubini 4 elimi- 
nate carbonic aeid more freely in the light than in the dark. 

That light energy influences the oxidation of the tissues 

[noted from Si rebel. I>ic Ver wenching des LtcJitea in dtr 

I 'In i i 

tted from Gcbhard and Moeller by FrcnnrL 

iK«M, \'..|. LV!I., P< l.M- 
'Quoted by Freuud 


is the consensus of opinion and the author believes that this 
is largely due to a direct action upon the blood itself. Ultra- 
violet and blue-violet frequencies are absorbed bv the blood 
better than by any other tissue. Physically it seems quite 
possible that the ultra-violet frequencies are in step or tune, 
so to speak, with the vibrational activity of the oxygen atom, 
in other words that there is a sympathetic resonance between 
them. • 

The observations of many experimenters on many differ- 
ent occasions tend to show that on both men and animals 
light energy has an influence tending to increase the oxy- 
genating power of the blood and the oxidation of the tissues. 

Moleschott, 1 Selmi and Piacentini" found that dogs, hens. 
pigeons and frogs eleminated less carbonic acid in the dark 
than in the light. According to Moleschott, the amount of 
the carbonic acid eliminated is in direct ratio to the intensity 
of the light. Still further it has been observed that with 
frogs and toads the blue frequencies of the spectrum are 
most effective in increasing the amount of carbonic acid 
given off, while with birds and rodents, the 'red frequencies 
had the most influence. This was observed by Pott/' Van 
Pech 3 found that beetles ( Hrunchus Pisi) consume more 
oxygen in light than in the dark. Scharling.' 1 Pettenkofer 
and Yoit/ 1 also Fubini and Ronchi," have proved that human 
beings give off less carbonic acid in the night hours tlnn in 
the day, even with absolute rest in the last instance. Fubini 
and Ronchi confined their researches lo a single limb, fore- 
arm and hand. 

As against these observed facts are the statements of 
Brown-Sequard, Pfliiger and others/ 1 who believe the in- 
creased elimination of carbonic acid is very apparent and 
occasioned by the movement and enlargement of the muscle 
under the influence of light energy. 

'Wiener MhL Wnrlu-n clirift. 1SS5. \.». 4^. 
*Reiuii ennti del He;de In^itutn I .Mini turd <li Si*. K. It-tin-. 11-70. 
Vol. III., Sit. II.. j>. si. rrf. Alltf. Med. Centr. Zttf.. 1X72. p. Hiu. 
"Quoted by Fremiti. 


It was found by S. Goodnew 1 that persons an ft animals 
to whom daylighl was accessible excreted more urine, urea 
and chlorides than those who stayed long in the dark. This 
is substantiated in the author's clinical experience. 

It has been proven by Moleschott, Bechard, Sehni and 
Piacentini, Pott, I 'linger and von Platted 1 that under the 
influence of light, through stimulation of the retina, marked 
elimination of carbonic acid and consumption of <> 
took place. 

Thi [so observed from experiments upon animals 

which have been deprived not only of eyes but even of brain 
and lungs as well, that tissue change may be influenced by 
reflex act inn through the skin. Certain of these points as to 
increased elimination of carbonic acid and tissue change 
under the influence of light energy have been refuted, hut the 
burden of experimental evidence as well as clinical fact is in 
favor of an influence U|w>u the former tending to its in- 
creased elimination, therefore increased consumption of 
oxygen and consequent action upon metabolism. 

According to the observations iyi GrarTenbergcr 1 and 
others among them, Bidder and Schmidt, the metabolism of 
carbon compounds is lessened m the dark, and more i 
formed and deposited. Animals kept in the dark, geese, for 
example, while being fattened, increase in weight. As tis- 
sue change goes on more rapidly under the influence of light 

energy this is what should be expected, viz.. a retardation of 
metabolism, because of this fact starving animals, men 
even who are deprived of food by the exigencies of life, 
I -xist longer if they may remain quiet in the dark, Tn the 
absence of normal metabolic change, the reserve nutrient 
supply is not consumed so rapidly as in light Fat is a 
product of imperfect oxidation. This physiological fact 
taken in connection with the preceding observed facts as to 

r Zur Lehrv v d, Einlluss d Sotmenll I Were, 

Kasan'sche Dissert., [823 

"Archives f .1 ges. Physiol., iK;^. XI . i>p 263, 272 

Mahler- w, I;,,, -. tfistt. Vol LIll. 


the relation of light to tissue change is of utmost importance 
in its practical application in the treatment of all conditions 
of imperfect tissue change or metabolism and by no means 
least of all, its rational use in the treatment of obesity, 
whether primary or secondary to some disease. 

According to Justus Gaule 1 the fatty l>odies lying next 
to the sexual organs in frogs disappear in winter time dur- 
ing the day and are formed again at night. This was ob- 
served with blinded frogs as well, showing that the light 
energy upon the fatty bodies takes place through the skin. 

The Influence of Light upon Metabolism. — That there is 
such an influence is demonstrated by the abundant proof 
provided in: 

(1) The influence of light energy upon the blood itself 
and the entire circulation. 

(2) The influence of light energy upon the tissue ele- 

(3) The influence of light energy, i.e., its stimulating 
effect upon the nervous system, producing increased ac- 
tion of the muscles (Pansini), and movements of the body 

(4) The influence of light energy upon the organs of 
sense, stimulation of the visual organs, thereby increasing 
directly or reflexly the energy of the functions of the body. 

The Influence of the Different Frequencies of the Spec- 
trum ujxm Assimilation and Disassimilation. — This subject 
was investigated experimentally by S. Daistch 2 and Pi. 
Kogan, 3 who formulated the following conclusions: 

(1) Red light weakens the processes of both assimila- 
tion and disassimilation; (J) green light stands lower than 
white, in regard to the accumulation of nitrogen, as well as 
to qualitative metamorphoses: destructive changes proceed 

■Centralbl. f. Phy-inl.. if mo. Vol. XIV. p. 25. 

'Uelicr drn Kinlluss drs wi'U^in I.irhtrs mid drr \rr>cliii-(l»-n- 
farhigen StraliK-n :iuf drn Gasan-tansoh lui Warmbhitrrn. IYut> 
burger Dissert.. 180 1. 

m LY1kt drn Kinllius «U-s \\i-U~cn (rUrtriscln.-n ) Lieliu-^ 11. ilrr 
vcrschiedcntarliimn Strahlni ant die Stt:ok-t<>tTnKtann>ri>liiiM' lui 
Thiurc-n. PrtiTsbiirgcr Dis-u-rt.. 1X94. 


more vigorous!) in green light; (3) yellow rind violet light 
induce the maximum of energy in all the vital proces 
more complete metamorphoses prevailing under the influence 
of violet light; (4I darkness causes a diminution in the ux- 
change of nitrogen in the body and incidentally, diminu- 
tion in the daily amount of urine. 

The Influence of Light Energy upon the Rcspi ration. 
Pulse, and Temperature. — In clinical work the author has 
observed an influence upon these functions from exposure 

of the entire nude body to light energy. P<>r example, in 
a given ease 13 observations of the pulse and tempera- 
ture were taken, in 1 [ instances the pulse dropped while its 
volume was improved in every instance. In each of the 
13 observations there was a rise of temperature, ranging 
from .1 to .8 of a degree. The exposure was made to the 
energy of a 15-ampere electric arc. This influence lias lieen 
demonstrated clinically in a large number of install 

( Observations have been made experimentally as to the 

influence of light upon respiration, pulse and temperature. 

I ere 1 found in One case lliat respiration was m; to the min- 
ute m yellow light, \y in green, and only 15 in red. Under 
the influence of red light the pulse becomes fuller and 
slower: in darkness it falls so greatly that the sphyg 

graph ceases to show oscillation. It was also observed by 
Goodnew* that the number of heart beats and the rate of 
breathing increased noticeably, while the animals upon 
which he was experimenting were under the influence of the 

Under the guidance of \V. von Bechterew, Trivtt* 1 
studied the influence of colored light on the pulse of health) 
persons, Mosso's plethysmograph was used in the experi- 
ments. The subjects were kept as a rule for two hours in a 
a! colored room of the clinical hospital. The plethys- 
m< .grams were taken a1 the beginning and at the end of each 

•lercscnce el Criminal It €, iKSK, quoted in Rami;. 
■Loc. cit 

y noted in Dworetzky and by Frenrul. 


experiment. In most cases colored light was found to de- 
press the pulse, that is, it became less rapid and full. This 
depressing action was most marked in the violet, least in 
the red. The action of the other colors correspond with 
their places in the spectrum, yellow excepted. This had no 
effect at all, probably because it permitted the passage of all 
the frequencies above it. It was surmised by Trivus that 
as every colored light ray formed in itself only one part of 
the energy of the complex of all the frequencies, or white 
light, necessary for physiological nerve tone, that colored 
light must be regarded as a form of light hunger, which 
produces a certain minus in the chemistry of the animal 
body. In other words, the effect of any one color may be 
explained not by its own action, but by the absence of the 
action of all the rest of the spectrum. 

According to Raum, light energy exercises an influence 
upon the daily fluctuations of temperature conversion of 
matter and excretion in human organisms, both healthy and 
sick. It is not only pulse, respiration and temperature 
which are affected by light baths, but there is secured better 
functioning of all the organs, with relief from the varied 
manifestations of impaired function. This influence has 
extended itself even to habitual constipation. 

In the weakening influence of red light upon the process 
of assimilation and disassimilation is to be found a rational 
and satisfactory explanation of the intense nerve and mental 
excitement of workmen compelled to labor in red-lighted 
photographic rooms, and in the excitement and delirium of 
smallpox patients. 

Nothing exercises a more untoward influence on the 
nervous system than imperfect metabolic change. The 
mental excitement, delirium, etc., could be accounted for 
(1) by the deficient nutrition which would result in con- 
sequence of weakened assimilation, and (2) by the toxic 
effect of the products of imperfect disassimilative proc- 
esses. On the other hand the stimulating effect of red 
light may, and probably is, in part, at least due to an action 



upon the nerve centres, and from the evidence the author 
is disposed to believe that it acts primarily upon the sett* 
cortex, and that the depression of die melancholiac is 
nnc through th«. centres. 

The Influence of Light Energy upon the Nervous 


Introduction. — It has been pointed out from time to 
time, both in discussing the physics of light and the 
rationale of its action therapeutically, that chemical action 
pertains frequency of the spectrum, to those of 

long wave length, and low frequency as well as to thos 
short wave length and high frequency, and that they were 
respect iv el y active according to the object upon which thev 
fall The frequencies are, therefore, thermal, luminous or 
chemical according to the nature of the body upon which 
they fall 

When light which falls upon a body is absorbed by u. 
one oi the three following results will follow: ( ! ) chemical. 
( 2 | thermal (3) electrical 

In the first instance, as in the action of light upon the 
blood and living tissues, the result produced by the chem- 
ical action is one of conversion by oxidation; in the second 
there will be no chemical change, hut the energy will he coii- 
l into heat. This will he shown in absorption phe- 
nomena In the case of substances colored with pure spec* 
inn 11 color; in the third the action of the light energy may 
give rise to electrical phenomena in two ways, by setting up 
electric currents, and by increasing electric conductivity of 
insulated substances. In common with the phenomem 
OOmpanying all manifestations of cnergj the course of these 
phenomena is seldom a simple one, but is complicated hy 
various simultaneous processes of similar kind. 

Aj w t the physiology of light energy as it relates to the 
living organism is not sufficiently exact to enable us to say 
just what is the action of all of the different frequencies, 


Of this we are certain, viz., that it is the short and high 
frequencies which chiefly affect most bodies. 

In the living organism different tissues and different 
fluids are differently affected by light, as is evidenced by 
their various absorption spectra. Blood corpuscles and 
albuminous substances give different absorption spectra. 
The energy of radiation is absorbed by the blood corpuscles 
at different degrees or wave lengths. Certain of the long 
and slow frequencies are absorbed, also the short and high 
frequencies of the blue and ultra-violet. Albuminous sub- 
stances, however, absorb the short high frequencies almost 

From a study of the absorption spectra of animal organic 
substances as well as the physiological effects upon the 
organism, their ability to react readily to the influence of 
light is clearly evidenced. 

The Action of Light Energy in Producing Motor Ex- 
citation. — Exposure to the action of light gives rise phy- 
siologically to movements by reflex as well as by direct 
action on the tissues of animals. Upon exposure of the eye 
to the energy of the green region of the spectrum, Dogel 
and Jcgorow 1 found that the circulation of the blood both 
in men and in dogs was very markedly changed by the irri- 

P. Bert 2 found that a chameleon, blinded in one eye 
became paler in color on the whole corresponding side of 
the body. That the color of the skin is acted upon reflcxly 
by light energy is also proved in other animals, the octopus, 
for example. A reflex action by means of the skin and eye 
thus affects the change of matter. 

The Action of Light Energy in Stimulating Other Nerv- 
ous Organs. — It is a recognized physiological fact that sud- 
den exposure to bright light will excite violet sneezing. 3 

'Quoted from Dworet/kv's Ref. Zeitsdirift f. tliiit. u. Plivsik., 
Ther.. Vol. V.. p. 165, by Fremid. 
"Quoted by Freund. 
"Landois and Stirling — Text-book I I11ma.11 Physiology. 

This phenomenon it doubt due to an action upon the 

sensory fibers of the trigeminus distributed to the conjunc- 
tiva. If the eyes are tightly closed, despite the tact that the 
red frequencies filter through the translucent eyelid, th 
position to sneeze disappears, This shows that it is the 
chemical energy of light which acts as an irritant, for upon 
opening the eyes, the inclination to sneeze is felt at 
which is followed by actual sneezing. The secreti 
tears may also be excited reflexly by strong stimulation of 
the retina by light. This comes through a stimulation of 
the first and second branches of the trigeminus, and through 
all the sensory cranial nerves < Demtschen'* 

The Influence of Colored Light upon the Xervous 
System — It has long been a matter of common observa- 
tion that different colors produce definite effects upon the 
senses and feelings. And it is also evident from many bio- 
al facts that light has a powerful influence upon the 
nervous system and the organs of sense. 

Red is always spoken of as a warm color, blue as a cold 
color, yellow as 2 cheerful color, green as 
etc. There is a difference in the way that different people 
are affected by color; one is pleasantly in by a cer- 

tain color, another is the reverse. This indicates a reflex 
effect upon the nerves. Some are in tune with certain fre- 
quencies, others with certain other frequencies, pointing 
an in h erent difference in constitution. BO to speak. The 
effect of light energy is not only Seen in the action upon 
the nervous organs, but upon the mental state as well. There 
are also many phenomena and modifications of vital 1 
tions which arise from its indirect action. 

In the "Uadecaying radiance of the sun man takes great 
delight/ 1 There is no natural phenomenon which prod 
Bd pi an effect upon the mind of man and his 

ttsness as light 

"The royal sun feedeth all," but it is not only physical 
food hut mental as well. Under the transition from dark- 

'Landota and Stirling: Text-book Human Physioioi 


ncss to light the stimulation of the mental power is greater 
than from any other form of energy. The withdrawal of 
this stimulus or reversion to darkness has the opposite 

Buedingen 1 from his experiments concluded that the 
reflex irritability of the spinal cord is not influenced by light 
rays falling on the skin. These experiments were made to 
solve the question whether light acts directly on muscle or 
through the motor nerves, when applied to the nerve muscle 
preparation. These experiments show that light as applied 
in the form of sudden transition from darkness to a blue or 
red light in concentrated form had no direct influence on 
nerve-muscle preparations made from frogs and further that 
it was not able to modify contractions caused by their 

He also made experiments with animals whose cerebri 
had been removed and in whom the nerve connection be- 
tween brain and spinal cord had been severed to determine 
whether reflex movements can be established by the action 
of light energy upon the skin. From exposure to the con- 
centrated energy of the blue and also of the red frequencies 
of the arc light spectrum, not the slightest trace of reflex 
irritability was observed. The experiments of Finsen show 
that ultra-violet rays act as a vigorous irritant to the nerve 
system and that by them skin reflexes are increased. From 
the nature of their action upon the skin (chemical) such an 
increase of the activity of skin reflexes and irritation of the 
nerve system would rationally follow. 

Schmidt, Ramplcr, and Ponct are quoted as authorities 
for the statement that psychical disturbances even to actual 
delirium have been observed in the eye hospitals where 
patients have been forced to live for a long time in the dark. 
Cases of different psychoses, following operations upon the 
eyes, are recorded by Frankt-Hochwart, I-andersberg and 
Elschning. 2 Numerous experiments were made by the phy- 

'ZciUchrift di;it. mid Physik. TlnTapic. Vol. VI., bk. 5. p. 272. 
"Quoted by Pansini. 



siologisl de Parville 1 with the different parts of the spectrum 
These experiments, referred to constantly in the literature ol 
photobiofogy, convincing!) show that the red frequencies act 
as excitants to the nerves, The recent experiments of 

ini point in the same direction. De Parville's experi- 
ments demonstrated a calming effect from the other end of 
the spectrum, attributed to ti . blue and violet fre- 

quencies. Another physiologist 9 has produced sensations 
of famines* by » e to red light and afterward the 

symptoms have been removed l»> exposure to the conjoined 

red and green frequenci 

In a large photographic plate manufactory, it was noted 
that a change of color in the light of the workroom from 
red to green acted to materially modify the excitability of 
the workmen. They were singularly lively over their work. 
singing, arguing loudly am) gesticulating vehemently, They 
became much quieter after the change. 

Goethe in his "Farbenlchrc" or in his "Theory of 
Colors" 1 called attention to the connection between colors 
and certain emotions, He observed that red and yellow light 
energ] Ised a bracing effect, while green and blue were 

depressing. The observations of Baron Reichenbach* were 
to the same effect. 

Akopenko,* who worked in the laboratory of Bechtrew, 
proved that the duration of psychical processes is unques- 
tionably affected by the energy of the different parts of the 
spectrum. A more invigorating and stimulating effect is 
noted from the effects of the colors nearest to the heat rays 
The mood of the person under observation is affected; in 

red light he feels brisk and cheerful, inclined to move and 

J J. P. T M Dec 15, 1900. Taken from Pharmaceutical Journal, no 
"Journal of Phys. Then, Dec. I|, n>««> 

Tin student will find TyndalPs ("New Fragments") analysis 
of iliis work of Goethe, of interest showing the misapplicati 
physical principles by author but bis richness in 
[noted by Freund 
'Quoted from Dworeteky's Refer, Zcitschr. f. diiit. u. ph> 
Th > VOL \ r „ p. 165, by Freimd. 


act. Physical effects are noted ; for example, at the close 
of the sitting headache has sometimes disappeared. Yellow 
light comports itself like daylight. It has no special effect 
on the quickness of physical reaction nor on the tcmjKTa- 
ment. The shorter and higher frequencies from the green 
up have a depressing effect. A prolonged sojourn in a room 
with green light, which at first is pleasant, becomes later on 
very oppressive. Psychical processes are retarded under its 
influence, mental quietude results, movement is checked 
and excitement allayed. The effect of violet light is still 
more depressing. The mental attitude becomes dreamy, even 
melancholy; after some time headache is experienced. The 
psychical processes become very slow and are checked, while 
the feeling of general depression becomes almost unen- 

The Influence of the Red and Blue Frequencies of 
Light upon the Excitability of the Cerebral Cortex. 

Introduction. — The recent experiments of Raffaele Pan- 
sini 1 upon the electric excitability of the cerebral cortex 
under the influence of light are confirmatory of de Parville's 
experiments as well as of a considerable amount of biological 
and clinical observation. 

Pansini calls attention to the expression of sadness 
acquired by those who are blind. There is a sobriety as well 
as sadness of mien, in contradistinction to the joyousness of 
mood and alertness of mind, experienced under the influence 
of the radiant energies of the sun. There is no question as 
to the influence of sunlight upon the spirit of the individual. 
Pansini speaks of the cerebral excitation and mental dis- 
quietude referred to on a preceding page, produced in 
those forced to carry on their avocations in a room with red 
glass in the windows, so extreme that it was necessary to 

^echerches Experimentale Sur I/Hxcitabilite filectri<|ue de 
1'ccorce Cerebrale par la Luniiere Rouge et I~i Lumiere Bleue, by 
Raffaele Pansini. Revue Internationale d'filectrotherapie et de 
Radiotherapie, Nov. 1903. 



replace the red glass by glass of green coloring. According 

to i lie same writer. Gourmand reports 4 instances of 

Station in patients with smallpox, who 

in a red loom. So great was their mental distress that 

they begged to t>e taken into the light. 

< >lenikofT noticed the same condition in smallpox patients 
of the clinic of Tschistovitsch. who were stibmitn 
red light treatment. They suffered from delirium with 
frightful hall ue in which at once passed a way upon 

their beta light room. In this same connec- 

tion Pans in i called attention to the state of fury or excite- 
ment induced in the bull 1> - with red coloring. These 
facts have led to the e< inclusion that the frequencies of the 
red region are to In- regarded as a dynamic agent, and an 
tnt to the nervous system in general, hut especially to 
the psychic functions. This view is endorsed by Binet, 
here and Gilles de la Tourette. 1 

According to them the nerves are also strengthened by 
the energy from the red region. 

Trm-im - Experiments. — By his experiments conducted 
at the Institute of Physiology of the Royal University of 
Naples, R. Pansim has attempted an elucidation of the prob- 
lem, lie endeavored to study the modification of electrical 
excitability under the influence of (1) blue light, (2) red 
light. To this end dogs were selected and trepanned in order 
that the motor area or sigmoid convolution of the cerebral 
cortex could be exposed to the action of the light. The elec- 
trical tests were made both before and after exposure to the 
different light energies. Pansini does not regard the number 
of his experiments as sufficient from which to draw definite 
conclusions, but presents in his report the more important 
effects noted. The greatest care was taken in the technical 
management of his work to prevent any error which might 
have falsified the result of his researches. Very feeble cur- 
rents were employed at not too frequent intervals, and an 

m£e £lectrique, n>m, p. gfl& 


equal pressure of contact in the different tests applied. In 
addition a long period of repose was permitted each time 
that the animals presented an approach to an epileptiform 
convulsion from the stimulating action of the magneto in- 
duced ("electro-faradic") current. Care was also taken not 
to permit the slightest elevation of temperature in the tissues 
influenced by the colored lamps, while the normal excita- 
bility was carefully guarded. Pansini in estimating the 
results obtained considered (i) the diverse intensity of the 
reaction established by the electric stimulant; and (2) the 
diverse intensity of the stimulant necessary to provoke reac- 
tions in the muscular group stimulated. His results in the 
latter respect were negative, and in a degree contradictory. 
Twice in 30 observations he had to apply the secondary of 
a Du Bois Reymond coil to provoke reactions after the in- 
fluence of the blue light. Two proofs out of 10 he regards 
as insufficient for formulating the conclusion that blue light 
renders necessary a greater stimulation to excite the cortex 
in the same manner, nor was he sure that the reactions were 
produced from the action of the red light. There was but 
one instance following the use of the red light, where the 
reaction extended to 2 centimetres of the secondary; in all 
the other researches it never reached anything like it. The 
contrary effect is sometimes produced, rendering it necessary 
to apply the secondary after the action of the red light, to 
secure reactions, especially when bandaging the eyes of the 
animals. From this single instance the conclusion that red 
light exaggerates the electric excitability of the cortex is at 
once impossible and unscientific. From exposures to blue 
light it was found that although the depressing action upon 
the excitability of the cortex was wanting in part and in 
others absent entirely, that in the great majority of the 
observations made, it reduced the reactions of the same 
brain to a minimum, and that the same brain, both in normal 
conditions and after exposure to red light, gave epileptiform 
reactions. Pending the use of the blue light, these reactions 
were constantly reduced to some simple muscular jerks. 



Despite the many possible sources nf error* both in valua- 
tion and interpretation of the phenomena encountered, the 
results noted cannot be doubted. The conclusion as to the 
depressing action o! the bine light upon the motor area of 
the cortex, is not based upon any elastic differences such as 
the differences between a muscular shock more or less 
energetic, more or less prolonged, but upon the important 
phenomena of tetanus and epileptiform attacks. These are 
absent after the use of the blue light, although present 1" 
fore its use under ordinary conditions and recurring after 
exposure to the action of red light. Blue light, therefore. 
Pansini affirms, has the property of reducing to a minimum 
the reactions of the cortex and also prevents the action of 
the stimulus which is exercised upon it at one point, from 
the Other motor areas. This, Pansini concludes, 
seems but rational when the analgesic action of light i> con- 
sidered, and its power to annul sensibility to touch and pain, 
as shown by his own experiments. Physiologically, it is 
n that all anaesthetic agents, morphine, ether or chloro- 
form, for example, when applied to the cortex diminish or 
suppress entirely the excitability of that part. The blue light 
is thought to act in the same fashion, and from this point 
of view be regards the effects observed as perfectly ex- 
plicable. The electric (magneto-induced) excitability 
not completely abolished in the majority of instances, 
therefore it cannot be regarded as establishing a true 


In conditions of mania where it might l>e supposed that 
physiological stimulation would increase the excitability of 
the cortex, the action of blue light seems to produce a tran- 
sient calm. Because of the great penetration of these fre- 
quencies, the brain is undoubtedly affected even through 
the cranial cast (Dbhr jansky ) « Even so the author thinks 
it entirely within the bounds of physiological action that the 
action of the chemical frequencies of light upon the 
peripheral circulation of the overlying tissues of the cranium, 
may affect the deeper circulation of the brain itself, and that 


this may result, so to sj>cak, in securing an unloading of 
congested areas, or a return to more nearly normal condi- 
tions. This is what happens from the action of light on an 
inflamed joint, for example, not a light thermally active, hut 
a cold light, and the one is to a degree just as reasonahle 
as the other. 

When the eyes of the animals experimented upon were 
carefully bandaged, so as to exclude any jxjssiblc effect upon 
the visual organs, there were no modifications whatever in 
the effects produced by the action of the blue light, which 
simply substantiates the theory, that the results obtained 
are due to the penetration of the chemical frequencies and 
their action on the circulation. This action by reason of 
anatomical conditions can only be limited in comparison 
with the action obtained in deep-seated skin lesions. The 
action of red light seems not so clearly proven, as in the 
majority of instances, Pansini found that it gave the same 
reaction as in ordinary conditions. Twice only, when non- 
existent before, were epileptic convulsions produced under 
its influence. In numerous other instances, however, much 
more energetic and more prolonged reactions (so to speak) 
were produced under its influence, but of exactly the same 
nature as under ordinary conditions. 

Throwing out of consideration the experiments which 
are of questionable value, there remained but 2 positive 
proofs of increased excitability of the cerebral cortex under 
the influence of red light, as against 8 negatives, which 
Pansini wisely concluded were too few from which to de- 
duce a law as to increased excitability of the cerebral cortex, 
to electric stimulation under its influence. 

It is suggested that the action of red light is not a direct 
one, but that it is best explained by the way of the visual 
organs. This theory is in accord with P»clliiii's observa- 
tions, and also with a very great deal of clinical observa- 
tion. Whenever the eyes were bandaged, Pansini found that 
a much more intense stimulation was required to provoke 
reaction than was true v. hen they were exposed to the action 


Lit J 

of light, c )iu deduction only can be made at this time, from 
the ex p erim ental work done, viz., that red and l 
frankly exert directly opposite effects upon the excitability 
of the cerebral cortex. Further experimental observations 
arc to be made by Pansini. to more fully elucidate this inter- 
esting pn ibteoL 

In extreme conditions of nerve exhaustion associated 
with a very considerable anaemia, the author has observed 
a very great desire on the part of patients to have 
fabrics almost exclusively for articles of dress. This was 
very marked in a woman physician, who had exhausted the 
supreme nerve centres, motor, vaso-motor, sensory and in- 
tellectual, and who was also profoundly arcemic. During 
several years of ill healtb her dress, cloaks and hats were 
almost exclusively red. There was an intense craving 
the color, and none other seemed to satisfy the need, while 
black, which she had been in the habit of wearing before her 
illness, produced a feeling" of profound depression. With 
iiia and an increase of nerve energy, the desire 
for red fabrics grew less, while with further improvement, 
characterized by still greater nerve force arid disappearance 
of anxmia, she no longer cares to wear it. But whereas 
formerly the brain was profoundly anaemic; and the supreme 
centres well-nigh exhausted, there has superseded a condi- 
tion of more or less cerebral congestion, aggravated by 
over-anxiety or application. Since this condition 
tablishcd there is an aversion to the wearing of red fabrics 
and red generally because they prodti satson of dis- 

and discomfort in the cerebrum. This patient had 
earlier in life suffered from insolation. Her observations 
are worthy of attention as she approached an analysi 
the matter with a specially trained intelligence both In 
physics and in medicine. 

r.Ine light on the contrary is regarded as exerting a 
quieting influence upon the cerebral system. In marked 
contrast to the feelings of joyousness and gayety induced 
hv red tight, is the sense of quiet, even sadness, aim 


by violet coloring, which is regarded as the emblem of 

In experiments made upon dogs by washing away the 
cortex cerebri, Goltz 1 found that after a sufficient amount 
of gray matter had been removed, and the animal had re- 
covered from the immediate effects of the operation that 
there was established peculiar defects of vision and other 
sensory defects. There seemed to l>e established a con- 
dition of "psychical blindness." The animal is not blind, 
can see and use his eyes to avoid obstacles, for example, but 
seemed to fail to recognize food or flesh as such when placed 
before him. The following observation is of especial interest 
in a study of the action of the red frequencies of light upon 
the cerebral cortex. Goltz caused his servant to dress him- 
self in a mummer's red colored garb, which previously had 
greatly excited the dog, but after the operation the animal, 
although not blind, was no longer excited by it. This 
would seem to indicate that the sensory cortex takes cogni- 
zance of these frequencies. In the neurasthenic patient re- 
ferred to, who clothed herself in red almost entirely, there 
had been marked congestion of the sensory cortex prior to 
the extreme exhaustion of all centres, sensory included. 
There had been no injury as with a traumatism other than 
insolation, simply a loss of energy with diminished func- 
tion. The penetration and absorption of frequencies of the 
red region seemed to supply a needed stimulus. The in- 
dications were for exposure to the radiant energies of the 
sun, but by reason of the necessities of the case and en- 
vironment, as well as because of the previous insolation 
there was but one course to pursue, and that involved the 
spending of the hours other than those demanded by pro- 
fessional duties, very quietly indoors from one month to 
another. In the dog whose cerebral cortex was washed 
away, there seemed no response to the periods characteriz- 
ing the vibrational activity of the red region of the spec- 

*Landois and Stirling. 



trum, although vision as vision was intact, This is but one 
of the many different phenomena which appeared from 

enmeni- :z. It is only instanced her* 

cause of a certain evidence which has been accumulated 
from time to time tending to show that there is some definite 
relation b e t w e en this part of the spectrum and the stimuta- 
■i of the 

Poveau dc CourraeBes rcj>orts an instance ting 

man who p upon entering into a om, became 

sad and began to weep. Insane patients have heen at «1u- 
ferent tin to the influence of red and blue light, 

according to the form of menial disorder. 

Ponza (quoted by Pansmi } placed a melaucholiac of a 
sombre humor, and wit h a "taciturn frenzy" in an alt red 
After three hours spent there the patient was gay and 
smiling, ( >n the other hand, a maniacal patient, forced to 
wear the straight jacket, by reason of his mania, became 
after an hour and a half spent in a blue room much more 
calm. Another case of mania after a day spent in a tridtol 
room felt himself cured and left the asylum in got ><\ con- 
dition. Ponza has treated hypochondriasis by red light, 
mania by blue, while violet light was used for depn 
of the nerve forces, The editor of the [nventuo Medici, 
in Guatemala, 1 IS said to have noted the same fact Jo years 
previously. These experiments first made in ttalj were re- 
peated by alienists elsewhere; ( tee of the first to do so was 
von Paquet in an asylum at Moscow* but his results were 
entirely negative. Schleger, who made a large number erf 
observations, concluded that the blue light produced 8 
transient calm in only a limited number of maniacal r 
This calm which follows after a short time is of short dura- 
tion, iv nol followed by any dangerous consequent 
proportionate to the intensity of the light. 

In somnambulism, Charptgnon lias found violet lighl 
to exert ise a quieting influence. In those suffering from 

'Quoted by Freitnd 


pathological excitement, Uffelman finds that violet light 
exercises a quieting influence. More recently Joive has 
produced in the case of neurotic patients a quieting effect 
by the influence of violet light ; while Dcnys, availing him- 
self of the great penetrancy of violet light, has tried by 
means of it to influence the brain of the insane. The re- 
searches of Dobrjansky tended to prove their penetration 
even through the skull. 

If it is by Jhe penetration of the chemical frequencies 
that the condition of sunstroke or insolation is produced, 
there seems no reason why, in certain cerebral conditions 
involving over-excitation, there should not be sufficient 
penetration from exposures to blue light, suitably regulated 
to favorably influence the mental condition. The mode of 
action of these frequencies in such conditions, is at the best 
conjectural. From the fact that the blood and lymph serum 
are fluorescent bodies, and that the chemical frequencies are 
absorbed by them, taken in connection with the well-known 
action of blue light on certain substances other than those 
contained in the living organism, the author is led to be- 
lieve that it is by reason of a direct action of the light upon 
the blood itself; its function as a radiant energy transformer 
is stimulated. This light energy unquestionably is con- 
verted into chemical energy, as is shown by increased oxida- 
tion due to an increased storage of oxygen in the red blood 
corpuscles. Upon the storage of oxygen in the latter, the 
necessary oxygen saturation of the circulating media de- 
pends. In nerve and mental conditions the role of tox.xmia 
is one of paramount importance. As a theory of the action 
of blue light may be admissible until the facts arc estab- 
lished, it is suggested that because of the powerful action 
of the chemical frequencies of light upon the blood, the 
systemic toxic condition which is reacting upon the su- 
preme nerve centres is overcome through the increased oxida- 
tive power of the blood. The selective action in a series of 
maniacal cases suggests that the cases favorably influenced 
are those in which the over-excitation or maniacal condition 



is purely functional, due to a toxic or an anxniic condition, 
and that in others no< ^> affected, the mental condition may 
be due either to an organic change in die supreme nerve 
centre or the reflex of a morbid condition elsewhere in the 


There is afforded sufficient foundation for both future 
photobiologica] research and clinical observation in the re- 
lation of life to light and its action in many manifestations 
tit disease. 

Bellini believes that the quieting action of the chemical 
freqn if flight is induced by the general revulsive 

effed which it exercises upon the entire superficies of the 
body. This is undoubtedly, in part at least, due to a direct 
action upon the peripheral nerve endings, and is an effect of 
the action of the chemical light energy upon the tissues and 
their absorption by the blood. The same writer sue_ 
that the action of red light up^on the brain is brought about 
through the eyes and their intimate connection with the 
brain through the optic nerve. The exciting e fleets of the 
red frequencies he believes to be due to their action as a 
quick stimulant. \n suggestion is made as to bow they 
act, but by reason of their long length and infrequent rate, 
as compared with the chemical frequencies, they have a 
greater degree of penetration. ;is [g beautifully shown in the 
transillumination of any part or organ. Foveau de Cour- 
melles 1 regards colored light as an actuality in the treat- 
ment of mental alienation. In 1886-87, at ,nc Charity Hos- 
pital of Paris, J. Lu\ d that hypnotic subjects were 
sensitive to red as an excitant, and to blue as a depressant. 
Since i8()o, Foveau de Conrmelles has made observations 
at his dink, showing that the waking stale was affected 
in the same way. To the use f »f colored light, incandescent, 
in i8gi, be gave the name of "Chroniothcrapie/* the thera- 
peutics of color. 


'Revue Internationale d'filcctrctherapie d Radioth£rapic Jan., 
-ijii" icd by Foveau de Courmelles. 


The Influence of Light upon Muscular 

The Action of Light Energy in the Stimulation of 
Striped Muscular Fiber. — It is not known that light has 
any influence on the movements of striped muscular fiber. 
A good deal of study and experiment has been made as to 
the effect of light energy on muscle. 

Pansini's experiments seem to show conclusively that the 
action of chemical light energy increases the power to do 
muscular work. This would be expected from its action 
on the blood. 

The Action of Light Energy in Stimulating Muscular 
Work. — Equally interesting and valuable is the work done 
by Pansini on the biological action of electric light upon 
muscular action. The results obtained by him, although 
working in an entirely different manner, tend in the same 
direction as those of Finsen, Freund, P>ernard and Morgan, 
as well as a host of others, and are corroborative of the 
opinion held to-day both by the physicist and the physician 
that it is the chemical rays which have the power to pene- 
trate deeply to awaken reaction in the tissues, and are, 
therefore, capable of establishing therapeutic effect. 

According to Ricgcr the chemical rays produced motor 
excitation in the nervous system, while Parvillc has found 
that excitations of the peripheral nerves are also produced 
by them. Gerhard, Pfliiger, Cazenave, Raticr, Furie. Fos- 
sangreve, Aubinois nave all demonstrated that light has a 
direct action on the muscles and nerves. From baths of 
electric light Colombo found that the chemical radiations ex- 
ert a stimulating action on all functions of the skin through 
the bio-chemic action which they awake in the tissues. 
Because of all these facts, Pansini was led to undertake a 
series of experiments to find out it blue light could have any 
biological action upon muscular work. While the fact of 
muscular excitation by light has been recognized these are 
the first experiments made to demonstrate its influence upon 
muscular labor. 



f'ansini's experiments were made at the Institute of 
Physiology of the Royal University, Naples, 1 in the dark 
chamber devoted to phototherapy and with the ergograph 
of Mosso. The subject chosen for all the experiments was 
30 years of age, in perfect health, of normal structure of 
skeleton and muscles, but little used to muscular labor. 
Therefore the weight used in all the experiments was but 
one kilogram, The source of light was furnished b) lamps 

in Utie, white, and red glass of 50 candle-power each, and 

each was provided with a metallic reflector on a univ 
joint. The lime was regulated by a metronome, registering 
84 beats a minute. The conditions of the subject were kept 
the same as far as possible every day. Right tests a day, 
in two series of 4 each, were made, an interval of 20 min- 
utes being allowed for rest in the open air between the two 
series, and also a 5 minutes rest between every two t 
ErgOgraphic tracings, showing exactly the amount of work 
done by a normal muscle unacted upon by any extraneous 
inlKlencc were first made. Every test made under the in- 
fluence of light was also accompanied by its ergographic 

As a result of these experiments it was found that ( 1 ) 
blue electric light exerts a favorable action upon muscular 
work in increasing energy and resistance; (2) that the 
favorable action Upon muscular work is explained by the 
Influence upon the muscles in activity which light exerts 
upon the muscles then | 3) the favorable action is not 

in every case proportional to the time in which the blue 
light has acted on the muscles. For example, muscular worl-; 
is positively increased by exposure to blue light during 
15 or 20 minutes, but with longer exposures (an hour) 
there is a rapid increase of muscular activity which 
lily fails. This was beautifully shown in the tracing 
after the hour's exposure. (4) The effects of blue 

'LWtiun Biologiqtse de la Lumi&re felectriquc, Sur k Travail 
Muaculairc. Par k Dr. K Pansini. Revue Internationale Tfelectro- 
Lher&pic d de Radiographic, October, 1903. 


light upon muscular work diminish in proportion to the time 
elapsed since the exposure ; (5) the action of blue light upon 
work probably corresponds to the speed of material exchange 
in the muscles, which are the true organs of motion, since 
the action of the colors of the spectrum upon nervous excita- 
tion is not yet surely proven; (6) action upon muscular 
work is an attribute of blue light and not that of other colors 
of the spectrum, since white has no influence, and red de- 
presses raiher than stimulates muscular work. Since red 
depresses muscular work the conclusion is forced that it 
has no bio-chemic effect upon the blood or muscular struc- 
ture. It is dynamic and especially addressed to psychic 

Pansini's work is accompanied by ergograms, each test 
showing the effect of blue light, red light, and the absence 
of effect of white light. These ergograms are most 
graphic illustrations not only of the number of muscular 
contractions but of the change in amplitude as well. In the 
test for control the amount lifted in the first test was 1736 
kilograms; in the second, when the muscles had not re- 
covered from the fatigue of the first but 1,455 kilograms. 
On exposing the arm to a beam of light from the blue lamp 
the work done for the test with muscles already fatigued by 
the two tests of control, was 1.848 kilograms, an increase of 
112 kilograms over the normal. These experiments have 
not only a value in demonstrating the power of light upon 
muscular labor, but are extremely suggestive as well. The 
depressing influence of red light upon muscular activity, 
taken in connection with its well-known stimulating effect 
upon the nervous system, points to an action of the longer 
slower frequencies either directly or transformed into elec- 
tric currents, upon the nervous system. The depressing 
effect of long-continued exposure to the blue frequencies 
with their well-known vaso-dilatorv powers can better be 
accounted for. 

The Influence of Light Kncrgy upon the functions of 
Internal Organs. — There are modifications in the functions 



of internal OTgUiS to be ascribed to both reflex and trails^ 
ferred action of light energy, It is maintained both by 

I lolzknecfal and BlC that this is only an indirect action. They 

n that as it is the chemically active energy of Light 
which is effective and which is completely absorbed by the 

ma on the surface of the body, there can be no < 
Other than a direct one. Holzknccht goes further and si 
that he regards tight treatment of all internal organs as per- 
fectly Useless, I [e asserts that there can be nn curative action 

ised by Light energy below the surface, that there 
neither is nor aver will be any kind of irradiation available 
for the cure of deep-seated disease, for any irradiation which 
is effective deep in the tissues must at the same time destroy 
the upper layer of the tissue. In this, the author, in common 
with Freund, from whom 1 lolzknecht's statement is quoted, 
cannot concur The penetrant frequencies of light energj 
have do such destructive action. It is the ultra-violet energy 
which is largely absorbed in the upper layers of the skin. 
True, this lias a very decided action upon living tissue, but 
ii i- an action, so far as demonstrated, which is superficial. 
\\ uh powerful light intensity and long exposures, the | 

I I ant chemical light frequencies, from the blue to the violet, 
influence favorably the deeper tissues. This is shown in 
their effect upon the more chronic and deep-seated lupus 
processes in glandular enlargements and masses of exudate 
for example, an effect not necessarily accompanied by any 
destructive action upon tin- skin itself. 

The clinical use of light energ) comprising the entire 
spectrum in systemic conditions, demonstrates that there is 
an effect due to the longer and slower frequencies. Just 
what it is, just what the relation between effect and di 
of energy is not known, but it unquestionably exists. Tt is 
!i< ralize from a specific action of 1>nt one-fifth 
of the energv of the spectrum on specific tissues, nor for 
that matter to reach conclusions from i generalization. The 
frequencies of the spectrum penetrate more and more 
deepl ling to their place therein; the longer and 


slower frequencies of the red region penetrating the more 
superficial tissues completely. If the hand and ear or for 
that matter tissues of greater depth be exposed to the action 
of red light, the tissues arc transillumincd by it. 

That this energy penetrates without doing work seems 
incomprehensible. True it is the energy that is absorbed 
which does work, but red light energy must either be 
absorbed or transformed in the deeper and non-translucent 

Any energy capable of acting upon the skin, as do the 
chemically effective frequencies, blue, violet and ultra-violet, 
is an appreciable power. Hut they do more than that as has 
been shown in considering the physiological action of light 
upon the blood. As a green leaf absorbs all the waves ex- 
cept the green which are reflected, and a red rose absorbs all 
waves but red, even so, then according to physical laws must 
the red medium of the blood absorb all waves except the red 
and that absorption means work done, energy imparted, just 
as in the case of plants. 

"The extinction of energy in space or its absorption and 
consequent disappearance in matter is a deep-seated fact in 
nature. The appropriation and selection of waves by matter 
and their eventual return to space constitute the life of the 
universe, the ebbing and flowing of cosmical tides." 

To the author's mind it does not seem that living organ- 
isms, showing as they do so close a relation to and de- 
pendence upon the radiant energy of the sun, are any excep- 
tion to the physical laws governing other forms of matter. 
The blood shows Its absorption bands and is fluorescent, the 
lymph serum is fluorescent also, and it must be that the pene- 
trant frequencies of light energy affect other tissues than the 
skin, for all energy that is absorbed produces an effect in 
some way. All the energy of the spectrum is chemical but 
with a difference. In relation to the skin superficies of the 
living organism, the higher and shorter frequencies are in- 
tensely chemical. May it not be that the longer and slower 
frequencies, red, green and yellow are chemical in relation to 

3 o6 


other structures Of the body? The latter are known physi- 
cally to have a much more powerful effect on certain sub- 
stances than the shorter and higher frequencies ; for 
example, on dilute solutions of nitro-prusaide of sodium with 
sulphid of ammonia, on green vitriol, on metallic acid and 
arsenious acid, on sulphuretted hydrogen, sulphid of sodium, 
on cyanin and un certain plant pigments, chlorophyll, 
etc. From the action of light energy upon plants, it is 
very clearly established how important these longer and 
slower frequencies are for their growth and nutrition. 

Speculation is not proof, neither is an absence of 
dence. It has been the author's hope that the way rtiigbl 
open in the midst of a busy life to help to an elucidation of 
these questions. Here, however, it is only possible to sug- 
gest the possibility Of such a biological action and express 
the hope that careful investigations ina\ he inspired to de- 
termine whether or dot an exposure of the different tissues 
of the body to the action of the energy oi the various parts 
of the s pe ctr u m is productive of results. The author is con- 
ed that such investigations would neither he negative 
ROT without great value. According to L. Cadmus 1 , the 
coloring matter in dogs* gall is quickly oxidized, turning 
green and then losing its color in the presence of oxygen by 
the action of light. 

The serum of horses* blood is subject to the same phe- 
nomenon, i.e., it first becomes green and then loses color 
when it is kept accessihle to oxygen with access of light. 

That there is then an effect from light energy upon the 
living organism is shown: (i) By its irritant effect upon 
the skin, intense light producing inflammation. (2) By its 
action upon the sweat glands promoting perspiration, tins is 
true of chemical light energy as well as of thermal. (3 | By 
its direct action upon the blood and the blond vessels, dilata- 
tion. (4 ) By exposure of large superficial areas of the tx dj 
to the action of intense light energy there results an in- 



creased amount of blood in the superficial vessels and a de- 
pletion of the internal organs or viscera. (5) P>y a direct 
or indirect influence light energy modifies the transmutation 
of matter. (6) By the action of light energy in relation to 
motor excitation. (7) By its parasiticidal powers. (8) An 
excess of light stimulus (in common with too great an ex- 
penditure of any energy) is destructive and paralyzing. By 
it dermatitis, a prolonged erythema with tendency to recur- 
rence and insolation are produced. 


Sun Baths. Arrangements of Solaria, Method* o£ TUc ami 
Therapeutic Indications. Fuberculosis of Joints, Pulmonary 
Tuberculosis, Anaemia, Neurasthenia., etc 

Sun Baths. 

The Chemical Intensity of Sunlight Dependent upon the 
Season of the Year, Time of Day and Atmospheric Condi- 
tions. — I'nfortiiuately the sun's radiant energy is imt a] 
available for therapeutic purposes. It is Dot a matter of 
dependence upon the weather only, but upon Other cir- 
cumstances which affect the chemical intensity of the light. 
In considering light sources in their relation to therapeu- 
tic work, there must be distinguished the difference between 
the visual interpretation of light which is its physiological 

r <*r optical brigl and that which is intetp] 

by its chemical act inn upon photographic plates, upon bac- 
teria, or in the production of characteristic light erythema 
of die skin. 

The chemical intensity of sunlight does not coincide 
with its optical brightness* The former varies with the 
m of the year and the time of day; i.e., with the suns 
height in the heavens. There is the summer solstice and 
the winter solstice to be reckoned with, the morning ascen- 
sion, the noonday maximum and the afternoon decline. In 
summer, for example, the chemical action of the sun and 
the blue light of the sky are much more powerful than in 
winter. It is weakened in the spring and again in the 
autumn, reaching the minimum a bruit the 21 st of Decem- 
ber, It is less in the morning and in the evening than at 


midday when the sun is at the zenith. During the height 
of the summer the hours between 10 a.m. and 5 p.m. are 
the best. In the winter, however, it is necessary to wait 
until a later hour in the morning, and to limit the after- 
noon hours. The atmosphere also affects the chemical in- 
tensity of the sunlight as well as its optical intensity. The 
latter is weakened by about one-fourth during its passage 
through the atmosphere. There is a much greater loss of 
chemical energy than optical, and this loss falls most largely 
upon those frequencies so useful in chemical change, as in 
agitation of bacteria and in exciting skin erythema, viz., the 
ultra-violet. They arc absorbed in their transit from 
the sun to the earth. 

Solaria or Sun Baths. — "Man lives only by the radiance 
from the photosphere of the sun." 1 

In this radiance provided by nature there is available 
not only for purposes of hygiene and sanitation, but thera- 
peutics as well, the best possible form of light energy. In 
only one class of therapeutic work can exception be made 
to this rule, and that is in the treatment of skin lesions, 
where a concentrated light energy of intense chemical ac- 
tivity is required. That is to be had from the radiant energy 
of the sun but not at the surface of the earth, as it is ab- 
sorbed in transit from the sun by the atmosphere. There- 
fore the electric arc, a radiant sun in miniature which can 
be used at its source is preferred. 

By this solar energy everything within its radius is 
purified, every object it penetrates is disinfected, and as 
these pages have abundantly shown, every known form of 
germ life is either destroyed or its development arrested by 
the action of light energy. On clear bright days even in the 
more northern parts of the United States there is to be had 
a more powerful source of light than can be obtained arti- 
ficially, while in the more southern parts of the country this 
radiance is of still greater energy, and, therefore, better 

! E. Larkin : Radiant Energy. 



fur therapeutic purposes. If the sun had no atmosphere the 
surface would shine at least two or three times brighter than 
ll does with a blue-violet color, like the light of an electric 
arc, playing between two carbon terminals. 

When die sun 5- on the meridian, and allowance is 
made for absorption by air and glass, it illuminates a 
n 70,000 times as strongly as a standard candle placed 
at one metre from the screen* (A standard candle adopted 
h> physicists is made of sperm and burns T20 grains per 
hour, or 7.776 grams.) The distance of the sun is 150,000 
million metres. Square this, multiplv the product by 
70,000, and the result conies out 1,575.000,000 .ooa- 

000,000,000 candle-power. This is the quantity of light 
emitted by the sun. and is different from the intensity, for 
an immense >ur fare, even if not very brilliant, can radiate 
a large quantity of light, while the quantity of light emitted 
by any square unit, as a square inch or centimetre, deter- 
mines the intrinsic brilliancy. A mathematical computation 
shows that the still's carbon winding 190,000 times 

brighter than the candle flame, and 150 times brighter than 
a calcium light, anil from two to EoUT times more brilliant 
than the electric arc light, all of which lights appear as dark 
spots when held between the eye and the sun. 1 In this 
solar energy is to be found the simplest and most natural 
method of using light therapeutically 

The sun is only a private in the host of heaven, a sin 
gle star among millions, but he alone among the countless 
myriads, is near enough to affect terrestrial affairs in any 
sensible degree, and his influence upon them is such that 
it is hard to find the word to name it. it is more than con- 
trol and dominance. He is almost absolutely in a material 
sense the prime mover of the whote. To him can be traced 
directly nearly all the energy involved in all the phenomena , 
mechanical, chemical or vital. Cut off this energy even for 
one month and the earth would die, all life upon its surface 
would cease. This fact has always been more «ir less dis* 



tinctly recognized, but a practical application of its truth 
is not always made even by the physician, whose duty it is 
to bring to bear all forms of energy physical and medicinal 
in the prevention and treatment of disease. The daily de- 
tailed application of large and universal truths in nature, 
too often escapes observation. From earliest times the 
material supremacy of the sun has always l>een recognized 
by thoughtful minds, and for centuries its life-giving powers 
have received recognition. His royal majesty, the sun, has 
been made the foundation of religious systems, as with the 
Persians. Says Young, 1 "It has been reserved for modern 
times, and to our own century (the twentieth), to show 
clearly just how, in what sense and how far the sunbeams 
arc the light of earth, and the sun himself the symbol and 
vicegerent of the Deity. The two doctrines of the corre- 
lation of forces and the conservation of energy, having once 
been distinctly apprehended and formulated, it has been com- 
paratively easy to confirm them by experiments and obser- 
vation, and then to trace, one by one, to their solar origin 
the different classes of energy which present themselves 
in terrestrial phenomena, to show, for instance, how the 
power of waterfalls is only a transformation of the sun's 
heat." 2 

Sunshine, though broken in the rill. 

Though turned astray, is sunshine still. 3 

The same thing, continues Young, is true but a little more 
remotely but just as certainly of the power of steam, of 
electricity, and even of animals. To-day the thought is fa- 
miliar, but still the truth is often unheeded. 

Whatever work is done, is by the undoing of some pre- 
vious work. 

When we come to inquire for the source of the energy 
which lifts the water from the sea to the mountain-top, 
which decomposes the carbonic acid of the atmosphere and 

The Sun. 

"The Sun. Young. 

''Lai 1 ah I'.nukh. The Fire Worshippers. Moore. 



plant-foods i f the sod. which builds up the hydrocarbons 
and other fuels of animal and vegetable tissue, We find it 
always mainly in the solar rays. Mainly because, i 
the light and heat of the stars, tin- impact of meteors and the 
probable slow contraction of the earth are all real sour* 
energy and contribute their quota, but compared with the 
energy derived from the sun, their total amount is probably 
something like the ratio of starlight to sunlight, so small that 
it is quite clear, as has been said, that * 'a month's deprr 

! ar energy would involve the Utter destruction of all 
activity upon the earth." It is not only natural, therefore. 
that modern physical science but medical science a< well 
should make much of the sun. The study of solar phenom- 
ena and their relation to health and disease should he pur- 
sued with the greatest interest and solar diergj turned to 
account in maintaining the one and combating the other. 
The beneficent action of this energy was appreciated to the 
full by the ancient Greeks and Romans with their conveniens 
even luxurious solaria in which they could expose their nude 
bodies to its action, The lesteotts thej learned from 
practical experience should have remained with as to our 

The Construction of Solaria or Sun Maths. — These may 
be elaborate and expensive or very simple and inexpeni 
Wherever and whenever the sun shines and there is I 
had a few cubic feel ol space, whether within or without 
. there is ihe means to the end. An upper room no 
matter how small may be utilized ami the light permitted to 
fall m through an open window <>r hi colder weather tb: 
Hit glass of the window. \ more pretentious sun room can 
be constructed with glass for its roof as well as for the sides, 
arranged as in a ph er*s gallery, fn either event 

there should be provided, according to the case, the meal 
reclining <»r of walking about with the nude body exp 
to tin action of solar light energy. Verandas can also be 
utilized in similar fashion. If isure is not possi- 

ble, screens of sufficient length may be used. The light 


should fall perpendicularly upon the exposed superficies. 
Where the flat roof of a house offers a suitable resting place 
for a small roofless cabinet, an ideal sun bath may be con- 
structed. In the small areas back of city houses a simi- 
lar opportunity is offered. In them a roofless cabinet or a 
roofless tent will suffice. The interior can be provided with 
an easy chair, a couch or, if the patient's condition requires 
exercise at the same time, there is nothing needed but the 
tent enclosing walls. These should l>c high enough to secure 
the necessary seclusion from observation. I^argc yards may 
be arranged for solaria by surrounding them with high and 
continuously boarded fences. The interior can be arranged 
for all classes of cases, those requiring repose as well as 
those requiring exercise. These sun yards as well as sun 
rooms should be provided with the means of suitable hydri- 
atic applications. If sun baths are administered in the room 
of a house or on the roof or yard of the same, the bathroom 
facilities will suffice. In more ambitions sun rooms or sun 
yards in connection with sanitariums, these facilities as well 
as provisions for massage and an alcohol rub, should form 
a part of the equipment. There are comparatively few sick- 
rooms, taking the country as a whole, which cannot be con- 
verted into a comfortable sun room at some time between 
the hours of 9 a.m. and 3 p.m., when the sun's energy is 
most effective. To this end the bed or a cot can be placed 
directly before the window from which the sash has been 
removed and the patient placed thereon with the entire nude 
body exposed. If too cold to permit of the removal of the 
sash, the exposure may be made to the light after passing 
through the glass. Luckily there is but little loss here of 
the short and high frequencies or the ultra-violet because 
they have already been absorbed by the atmosphere. The 
sun's energy, with its complex of frequencies, its richness of 
those of the blue region, can be used by every practitioner in 
his daily rounds to the good of his patients, and when to the 
influence of light there can be added that of the air greater 
good will follow. 



It is a simple matter for example in the dressing of a 
wound, of an open malignant process, where the patient lies 
in bed in a beautifully sunlit room, to direct that the bed 
should be moved into the sunlight and Mk- one or the other 

exposed to the action of the sun's radiant energy not only 
during the process of dressing but at other times as well. 
The action may be limited to the visible chemical frequencies 
only if for any reasmi the thermal energy is undesirable by 
placing either panes of blue glass in the Window or permit- 
ting a blue glass screen to intervene between the patient and 
dl€ Window, To illustrate: The Btlthor was recently Called 
in consultation to a patient who for over three years had an 
extensive open sore as the result of the removal of a cancer- 
ous breast by means of pastes. The sore had never In 
and the condition had been aggravated by daily exposures 
for almost one and a half years to the X ray. The patient's 
skin was tanned until it resembled a negro's on the entire 
right side ol the thorax from the clavicle far below a hue 
drawn from the sternum and extending tinder the arm and 
far down the posterior thoracic walls. There was a large 
cavity in the axilla, the right arm was enormously swollen* 
metastases had taken place in the left breast, the discharge 
was foul and the patient was worn with the pain of this 
extensive destructive lesion. The attending physician 
wished to know if the use of light energy would render life 
more tolerable and wished the writer to advise as to a 
practical form of apparatus for the purpose. A considerable 
experience with the most desperate of inoperable pelvic cases, 
in which light was used as an adjunct to the X ray, had jus- 
tified the opinion that by its use, (l) the pain and discom- 
fort would be modified, (2) the odor controlled and (3) a 
possibility of stimulating the healing process. 
Immediately upon entering the pitient's room, the 
author was struck with the ease and facility with which the 
lesions could be kept for from 3 to 4 hours daily under 
the direct influence of solar energy, instead of being care- 
hilly secluded in the dark by interminable dressings. The 


windows were west and large, the river lay just below to 
serve as a mirror for the reflection of the waves of light. 

Baradat 1 recommends the giving of sun baths upon the 
sea, where the light is reflected by a vast mirror — the waves. 
This reflection of light by the waves of the ocean is an im- 
portant factor in the good results obtained from sending 
tuberculous patients to certain seaside resorts noted for their 
efficacy, as at Mentonc on the Mediterranean. The condi- 
tions for exposure to solar energy were ideal and the 
instance is related here that the reader may see and avail 
himself of every similar opportunity. The most powerful 
agents in our possession for the inhibition and destruction 
of micro-organisms are sunlight, fresh air and abundant 
nourishment. These were all provided in abundance, the 
latter was the first consideration and the saving clause in the 
case was the patient's good appetite, digestion and nutrition. 
The sunlight was at hand and was a factor in the well-being 
of the patient from its general diffusion in the room, but the 
concentration of its energy upon the sore itself, despite the 
well-known fact that open wounds do better than those that 
are shut in, had never been thought of. Thus every day we 
ignore the simple means to the end in our desire to reach out 
after the new and little known. 

Willard, 2 in considering sunshine rs. X rays in the treat- 
ment of tuberculosis, says: "In my own hospital wards T 
have always considered the sun porch as the most important 
of all the means of cure. Every tubercular joint confined to 
bed, cither with horizontal extension or with fixation or 
traction of joint, spends the entire day at all seasons lying 
directly in the sunshine, his eyes and head being protected by 
a green shade attached to the head of the bed. The effect on 
health, appetite and cell resistance is simply marvellous. 
When able to walk about, patients arc encouraged to play 
in the sunshine, not in the shade. I have not infrequently 

'Zeitschr. fiir Tuberculor-e und TTeilstattenwesen, I'-oj. Hd. V. 
Heft I. 

"Journal of the American Med. Ass., July 18. 1903. 



sent out into the sunlight and fresh air apparently hopeless 
cases of joint disease with lardaceous organs, and have had 
them return with sinuses healed, waxy changes arrested and 
health restored. Of course, it is necessary that surround- 
ing conditions, evi n in the country, shall be healthful, 
many farmhouses aw unsanitary in the extreme. In the 
treatment of tuberculosis of the joints not only are mechani- 
cal and operative measuo but all the aca 
conditions of health are essential: a superabundant 
easily digested and nutritious food, and clothing adapted to 
the surrounding conditions, in addition to the sunshine and 
air. There are few individuals who have not ohserved the 
influence Of darkness and poverty and vice on the general 
health, and yet few physicians realize the importance of 
securing the brighter and better conditions. The time is 
near at hand when sanatoria for the treatment oi tuberculo- 
sis of the hard parts, as well as those of the soft tissues, 
will be established. Outdoor life in tents, either in the pine 
's or in the hospital grounds, promises a simple practi- 
cal application of the principles enumerated. Cheeks will 

grow more rosy, flesh will increase, energy will improve, and 
tive power will speedily be such as to control and over- 
come the tubercle bacilli. 

"McKemrie and Galloway 1 have also adopted this most 
excellent principle of treating cases of tuberculosis of joints 
in the Open air by having them live in tents, thus giving 
patients all the advantages of sunshine and fresh air thai 
now in rogue in the lung tuberculosis sanatoria. The appe- 
tite is greatly improved under such conditions; more food is 
taken, and it IS belter digested, 

M Dr. Flick's regulations at the White Haven sanatorium 
for consumptives are just as applicable to joint tuberculosis 
as to phthisis cases; patients to live in tents and to spend 
their life absolutely out oi doors, air to circulate freely 
through sleeping apartments, ample bed covering to be sup- 

'Trans, Amcr, Orthopedic V X\ '., tgoo, p. 10. 


plied. Each patient to take at least 3 quarts of milk and 
6 eggs a day; more if possible. In addition, a good dinner 
in the middle of the day, and a light breakfast and supper. 
Dinner of roast beef, vegetables and dessert. The gain or 
loss in weight are the best indications for adaptation of 
treatment and food. 

"Poncet, of Lyons, and rerdu and Blanc 1 have also 
applied the method practically by exposing joints covered 
with iodoform gauze to the direct action of the sun for hours 
in the day. As the case recorded by them, however, had had 
a previous excision of the knee, the report only shows that 
the sun's rays acted helpfully in the cure." 

There are to be obtained distinct effects from the use of 
sun baths : ( 1 ) A tonic effect ; to this end a short exposure 
of the entire nude body to the solar energy is required. (2) 
An eliminative effect : a prolonged exposure without any at- 
tempt to minimize the thermal energy. (3) A nutritive 
effect; a prolonged exposure modifying the temperature in 
order to secure the action of the chemical energy where it is 
desirable to profoundly influence the nutrition of the deeper 

The latter is the method chiefly used by Finscn in his 
sun baths. The patients promenade naked in a sunlit yard, 
where everything is done to keep down the temperature of 
the skin. To secure this result the ground is frequently 
sprinkled or if necessary shower baths are used. Here the 
purpose is not to have a thermal effect but a chemical one 
only. By the penetrability of the blue-violet frequencies 
and their chemical energy they are able to profoundly modify 
the nutrition of deep-seated tissues and organs, hi the pass- 
ing and repassing of the circulating blood stream during 
such a sun bath, every drop of blood is brought under the 
influence of the light and revivified. The impartation of 
energy to the storcr of oxygen, the red blood corpuscle, is of 
first importance. 

In the second instance, it is not alone a question of the 

a Annales de Cliirurgie ct d'Orthopiedie, Vol. XIII.. lcjoo. p. 19. 


Li i.j ir ENERGY. 

chemical action of the penetrable blue-violet frequencies, 
although these are still active, but of the thermal as well, 
emphasizing the effect of the chemical energy upon the skin. 
An active condition of the sweat glands is induced b]f their 
combined action, which, however, may be brought about by 
r the one or the other alone. A slight perspiration js 
induced in the electric arc bath, always* noticed in the 
palms of the hands and over the sternal region first. 
This is never a warm hath. When the sun's heat <>r heat 
from Other sources is used extreme sudation is established. 
The use of sun baths in this way is indicated in all condi- 
tions where an climmative effect is desired primarily, 
IS in Obesit) f<»r example. In the first instance it is the tonic 
stimulating effect of the sun's light which is desired, and 
this is usually in a class of cases who are unable to bear 
an undue expenditure of energy of any sort. Under 
this head may come convalescent patients, who are still too 
feeble to withstand this mighty energy. A longer exposure 
than 3 to 5 minutes in very feeble patients may produce 
headache, lassitude, insomnia and depression. 

Light and Air Baths. — When the baths are adminis- 
tered in the open air, the action is due to the conjoined 
influence of light and air. These should be administered 
with little or no clothing for a period of from 2 to 6 hours, 
To keep themselves warm patients should ^\o some manual 
work, engage in gymnastics, or have massage. These baths 
should be taken morning and evening, with a sun bath or 
hot bath at midday. The effective factors with these baths 
are regarded as the thermal stimulus, the increased activity 
<*\ the skin through the radiation of heat and the influence 
of light on metabolism. The same factors are operative 
in prolonged sun baths in the open air where no effort is 
made to eliminate the thermally active energy. 

They are practically the sajjie as considered under the 
second subdivision, save that the purpose of the latter 
may be obtained within doors. A light and air bath acts 
as a general tonic to the nervous system, they are also very 


useful in the treatment of obesity, and arc good in congestion 
of the internal organs. The action of the heart and the 
kidneys is stimulated by them. They have been likened 
in their effects to those of the water cure. 

Physiologic Action of Sun Baths. — Under this head 
must be included all those physiologic changes which have 
been discussed under the physiologic action of light. It is 
an influence due not to a single frequency or group of fre- 
quencies but to a complex of all the frequencies of the spec- 
trum. These frequencies are thermal, luminous and chem- 
ical in relation to the different structures of the body, pro- 
ducing, therefore, the reaction due to their combined in- 
fluence. Thermal energy gives rise to an increase in the 
bodily temperature. This is also true, but to a less degree, 
of the chemically active energy. The thermal effects then 
produced are practically the same as those induced by other 
sources of heat, save that they are unaccompanied by the 
depressing effects so often experienced by the use of hot 
air, water or vapor. This is by reason of the chemically 
active light energy conjointly active with the thermal. 
The thermic reaction stimulates the heart, brain and other 
organs, and there is an increase in metabolic activity as 
well. This elevation of temperature may rise to 40° C, 
I04°F. Kellogg found that there was an increased pro- 
duction of carbonic acid, indicative of an increased con- 
sumption of hydrocarbon and carbohydrates, which occurs 
also when the body is exposed to cold. There is likewise 
an increased oxidation of proteid, a characteristic effect of 
all the measures which raises the temperature of the blood. 
From the thermic stimulation there results a dilatation of 
the cutaneous blood-vessels (evanescent as compared with 
the dilatation produced by chemical light energy). This 
in connection with the more energetic action of the heart, 
the quickened circulation, tends to accelerate metabolism 
throughout the entire body. The violent and prolonged 
hyperemia of the skin induces a determination of blood 
from the internal organs. l»v the overfilling of the cuta- 



neous vessels a considerable amount of blood is diverted 

the interior of the body, since when filled, the in 
of the skin may contain one-half to two-thirds of the entire 
amount of blood within the body. Xaturally a drainn 
all the viscera results, establishing thereby a collateral 
anaemia in the brain, liver, kidiu ach, spleen, and 

other viscera. The drowsiness which ensues i> a mai 
tatioii of oerebral ansemia. Because of this, the patient 
falls into a profound slumber. By the thermally active 
energy of the sun a profound effect is produced upon the 
em. This is abo true of the chemically active 
jv. and the one *>r the other is the more active accord- 
ing to the manner of administration of the sun bath. Simul- 
taneously through the influence of the thermally active 
a eat glands are stimulated to greater activity 
and, very active perspiration is induced. The amount of 
sweat may be increased from the normal of 2\ ounces 
in an hour to as much as 2 or 3 pounds, even more in an 
hour, especially if the patient is exercising actively. 

The action of the chemically active light energy upon 
the peripheral nerve endings also exerts an influence Upon 
the sweat glands. The effects obtained may be the one 
of three, ( 1 ) from a simple tonic action, where the com- 
bined energies of the different frequencies of the spectrum 
are utilized over short periods of time; (2) by subjecting 
the patient to the influence of the full en J lie sun 

over comparative!) long periods of time: (3) from the in- 
fluence of the chemically active energy whenever a means is 
Used to keep down the thermal effect, as by cooling the sur- 
rounding space, whether a sunlit yard or a sunlit room, by 
suitable means, sprinkling the ground, refrigeration of the 

r 11. ice d air. and by douching the patient with cold 

water. In the first in the action is that of a simple 

tonic, in the second profound el i mi native effects, and in the 
third fundamental nutritive changes are established. Each 
has its recognized indication in the various conditions of 
disease, and the one or the other must be prescribed with 


the same intelligent skill, basing the prescription upon 
physical properties, physiological action, and pathological 
conditions, as in the case of mercury or strychnia. It is 
not enough to tell a patient to sit or lie in the sun, but 
the points which have been enumerated must be care- 
fully considered in order that the needs of individual cases 
shall be met. The sun bath should be given in the fresh 
air wherever possible. In this way it really becomes a 
light and air bath, and as such accomplishes a twofold pur- 

Sun baths are of benefit (1) by promoting perspira- 
tion. As the result of this action harmful and toxic prod- 
ucts are eliminated. (2) Ry the stimulation of metabolr 
ism. (3) By stimulation of the nervous system, and (4) 
by the direct action of light upon the blood. This primary 
action upon the blood is after all the fundamental action, 
and upon it the round of physiologic changes known as 
increased oxidation depends. 

As to the bactericidal action of sunlight under the con- 
ditions governing a sun bath, it is not active. This is by 
reason of the absence of a maximum of ultra-violet energy 
at the surface of the earth, and also by reason of the little 
penetrating power of these frequencies. There is, how- 
ever, an abundance of blue, indigo and violet frequencies, 
and their bactericidal action is by no means to be disre- 
garded. Still the primary effect in the sun bath, in bacterici- 
dal diseases, is not one of bacterial destruction but one of in- 
creased physiologic resistance. In this way the balance of 
power, so to speak, is with the individual and not the 
bacteria. By establishing normal physiologic conditions of 
circulation, nutrition and elimination, the influence of micro- 
organisms need no longer be reckoned with. In all conditions 
of metabolic defect, and especially in conditions character- 
ized by deficient oxidation, sun baths are indicated. Obesity, 
diabetes, and the alloxuric diathesis are notable examples, 
and in this class of cases a prolonged exposure to all the 
radiant energy of the sun is indicated. 


The profound autointoxication of the patient suffering 
from chronic indigestion \ :n is dry, sallow, leathery, 

evidencing deficient oxidation, will be promptly relieved by 
the daily administration of sun baths. Under the infill 
of the sun's thermally and chemically active energy, the skin 
becomes moist, healthfully colored and smooth in texture 
because of the increased oxygenating power of the blood 
from the chemically active frequencies and the elimination 
of toxic products due to the free sudation established by the 
thermally active frequenci 

In no conditions is sunlight whenever it can be com- 
manded, of greater avail than in anaemia and chlorosis, Uv 
the stimulation imparted t<» the oxygen-staring capacity of 
the red blood corpuscle, the entire blood stream is thor- 
oughly 0J edj even to the remotest part of the organ- 
ism. Even though but a part of the body is exposed, the 
circulating medium passes and repasses through the super- 
tic lal circulation of the part exposed uulil in a very short 
exposure, the entire blood stream is brought under the in- 
fluence of the oxidating light energy. Still better ts the 
result when the entire superficies of the body can be ex- 
posed directly to its influence, for to each square inch oi 

surface there is an expenditure ol energy, and when this is 

multiplied by the number of square inches of the body 

the amount of this expenditure is increased a hundred- fold. 

its prolonged effect Upon the circulation the 
CUtaneou^ which results in chronic visceral conges- 

tion, is rapidly relieved. Elimination of toxic material takes 
place at the saute time. 

The sun bath is of very great value in the treatment of 
neurasthenia. When the conditions of season, weather or 
environment preclude its use, the electric are hath satisfac- 
torily takes its place. All forma of neuralgia dependent 
up«m impoverished blood and conditions of malnutrition as 
well as those associated with the rheumatic diathesis are 
benefited by sun baths. These are mentioned in contradis- 
tinction to those neuralgias dependent upon a traumatism or 


of central origin. Where the neuralgic pain is due to an 
injury with the formation of an inflammatory exudate, con- 
centrated electric arc light energy is indicated, if light energy 
is to be used. 

When employed with the proper precautions Kellogg 
states that sun baths arc of great value in myxedema and 
exophthalmic goitre. The author, personally, has had no 
experience in treating these conditions in this way. Wher- 
ever the condition is one involving the heart, great care must 
be taken in the administration of all forms of heat. This is 
true of sun baths in the same class of cases also, and to the 
end of preventing an untoward effect of the thermal energy 
upon the weakened organ, ice bags or a cold coil should be 
placed over the precordium. 

Sun baths in common with artificial light baths are use- 
ful in Bright's disease and also in other forms of visceral 
degeneration, cirrhosis of the liver, for example. In these 
conditions great care must be taken in their administration. 
Neither too violent nor too prolonged expenditure of radiant 
energy must be made. The patient must l>c properly cooled 
after the bath, the means for that purpose selected according 
to the individual needs. Tn these cases, as a rule, the cold 
water plunge, swimming bath, cold douche even, are unsafe 
and the indication for a tonic application of cold is best met 
by friction with a cold mitten, a cold towel rub or a cold wet 
sheet used in the same way, the temperature of which should 
not be lower than 6o°F. and for no longer than from to to 20 
seconds. Reaction must be established in the gentlest and 
safest fashion, in order not to unduly load up weakened 
organs by the return of the circulating fluid to the interior of 
the body. 

Sun baths arc also of value in chronic rheumatism, in 
rheumatic gout, in tuberculous joint diseases, in tuberculo- 
sis, asthma, and also in affections of the skin and mucous 
membrane. In fact, the range of morbid manifestations in 
which sun baths are of value is just as wide as the entire 
range of disease. Seldom are the conditions such, save in 


the very crowded centres, that this afl-perradifig radiant 
energy may not be utilized for the purposes of hygiene, sani- 
tation and therapeutics. 

Technique, — In so far as possible sun baths should be 
arranged to open to the south. The time of day in the 
summer may vary* from 10 a,m. to 5 p.h. These hoars 
will need to be lengthened in the morning and shortened 
in the afternoon as the season approaches the winter sol- 

The duration of a single exposure is governed by the 
object to lie obtained as indicated and also by the season of 
the year, the condition of the atmosphere and the time of the 
day. The head and eyes should be protected from the 
direct solar rays by the use of colored glasses and suitable 
awnings or umbrellas. To this end the head should be pro- 
tected. Parasol* of dark color (black) should be used, or if 
edition of the head necessitates greater precautionary 
tires, cold wet cloths should be applied, covered in turn 
with some dark fabric or a dark colored umbrella. Should 
the patient have previously suffered from insolation, the need 
ire is still greater. Nausea and other unpleasant symp- 
toms may arise through an undue stimulation and over exci- 
tation of the brain and central nervous system. If the whole 
mi if air c if (he body is exposed to the direct solar ravs, the 
head should he still further protected. This to avoid any 
direct action upon the cerebral circulation, as that secured 
indirectly through the action of the light upon the body cir- 
culation is sufficient. 

Tin" whok hairy scalp of men and children may he 
moistened, a}80 the Utcr, The same is advised tn women, and 
where it is undesirable to wet the hair a napkin wrung out 
uf water al a temperature ol from 6o° to 65 F. should be 
applied to the face and neck, and this may be supplemented 
at m< 1 bj an ice cap to the head. The napkin should 
be re WCl with cold water tf the exposure extends over a 
minute Of tWO. The necessit) for these precautions 
does ii"( exist after patients have become accustomed to 


the bath except in cases which have suffered from sun- 

The entire body should be nude. In sanitaria where com- 
mon sunlit yards or gymnasiums are used for both sexes at 
the same time, the need for clothing may be met by the use of 
bathing attire. If clothing is necessary, it should be white or 
light colored, as a considerable portion of the light energy 
will reach the covered portions of the body through the 
clothing. Feeble patients should preferably recline during 
the exposure. Vigorous patients, on' the other hand, may 
walk about the outdoor solarium, and, if provided with a 
gymnasium, engage in light gymnastics or games of some" 
sort. If the purpose be to increase oxidation to as high 
degree as possible, as in obesity, diabetes and the liihiemic 
diathesis, active exercise is indicated. 

Frequency of Treatment. — The best results are secured 
by daily exposures, and the duration should 1>e increased 
from 30 to 60 minutes at least once a day, according to the 
patient's toleration. 

Summary of Direct Effects of Sun Raths. — ( 1 ) A more 
or less pronounced erythematous reaction of the skin, lead- 
ing to intense pigmentation and desquamation; (2) profuse 
perspiration; (3) rise in temperature; (4) nervous dis- 
turbances in unduly sensitive persons, and a pleasant sense 
of refreshment and comfort in healthy or less sensitive 
persons; (5) improvement of appetite; (6) improved spirits, 
and (7) better sleep. In a word, the general power of as- 
similation is promoted. In this way the vital energy of the 
body and its power of resistance to all injurious influences 
is greatly increased. 

Sun Raths Indoors. — When sun baths are given in- 
doors all hangings should be dispensed with, for by the 
time the light has filtered through them, even white muslin 
and lace, much of the initial energy is lost. Furthermore, 
they become dust laden and afford a suitable lodging for 

Direction of the Incident Light. — The light both indoors 



and nut of doors should preferably fall perpendicularly upon 

the mule bod 

Insomnia forms nn indication for the use of carefully 
graduated cold applications to the head, tare should be 
taken nut to overheat the head during the hath. The bene- 
ficial effect of the cold application to the head may he sup- 
plemented by the use of a cold spray applied f<*r 10 <>r 15 
Mis to the legs and feet. Each pathologic condition 
must hi- suitably met in the after treatment. The cold 
douche or spray should he neither too intense HOT too pro- 
longed in rheumatism, gout ami rheumatoid arthritis, for 

Tubercular patients must lie cared for carefully in this 
rd, and may HOI necessarily require the use of a cool- 
ing application. The systemic condition of the patient and 
the amount of reaction established by the solar energy must 
govern the physician's prescription. It ma\ he well in some 
cases to use a tepid shower »>r a fan douche, or even the in- 
terrupted jet at the beginning of a treatment for the pur- 
of cooling a patient. For this purpose a temperature of 
from 75 to 8o n or B5 R may be used, and the duration 
of the application for from a fraction of a minute to a full 

After Treatment. — This should take the form (1) of 
cooling douches, sprays, local applications or rubs; (2) of 
exercise. In both instances the object is to promote a 
healthful reaction. In cases for which an administration of 
a cold douche is indicated, it should preferably he made to 
impinge upon the legs, hack and liver, care being taken to 
avoid the precordial region. In cases requiring great care 
in this particular the patient should preferably be cooled by 
a rub with a cold wet towel or sheet. The presence of skin 
eruptions forms a contraindication to friction, nor is it best 
to use very cold applications, A rain douche at 85°F. is 
recommended. In this class of cases the necessary reaction 
would better be established by exercise. In the treatment of 
painful joints, the force of the impinging "louche should not 


be permitted upon a sensitive part, as the pain will thereby 
be increased. 1 

Contra-Indications and Precautions. — The sun bath is 
contraindicated in all febrile disorders, save in cases of 
pulmonary disease with slight elevation of temperature. 
Whenever the febrile activity is of a decided character in this 
class of cases the use of sun baths is contraindicated. how- 
ever. Or in this same class of cases, if there is no great 
rise in temperature, they should be limited to the tonic effect 
only, and to that end exposures of but a few minutes should 
be made. 

When there is a disturbance of the functions of the body 
giving rise to an increased temperature, it is an easy matter 
to still further induce increased temperature, therefore the 
necessity for great care. The skin reaction is more severe 
in blondes than in brunettes and with the latter measures 
may be indicated to soothe the inflamed skin. l ; or this 
purpose dusting with starch, talcum powder, or the use of 
oxide of zinc ointment may be necessary. If there is much 
swelling induced, cooling applications in the way of com- 
presses may be indicated. The trouble is avoided as soon 
as pigmentation of the skin is established. 

Conclusions. — The body superficies in part or as a whole, 
according to the environment of the individual, should be 
exposed daily to the influence of the radiant energy of the 
sun. This should be done for the purpose of maintaining 
normal circulatory, oxidative and eliminativc conditions even 
in health. The custom of many individuals of spending 
hours of the day during their sojourn at the seashore clad 
only in scanty bathing attire is a commendable one. from the 
point of hygiene, however a critical and perverted mind may 
regard it from a point of taste. Less cumbersome and light- 
excluding attire at all times and seasons would redound to 
better health : while too much stress cannot be laid upon the 

'For full directions as to the scientific use of hydriatic measures 
either alone or in connection with *un or artificial light baths, the 
reader is recommended to the work of Or. Simon Raruch on this 



necessity tot abolishment of curtains, hangings and drap- 
eries, no matter how much their presence appeals to the 
artistic sense. 

The exposure of the unprotected head to the sunlight, 
if the energy be nut too great, will not only often prevent 
the premature falling of the hair, but it will in many cases 
arrest the trouble- For a number of years it has been the 
author's custom to direct patients thus troubled to go with- 
out their hats during their summer's vacation and even in the 
city. Especially has this been done for men patients, where 
treatment has been instituted by means of artificial light in 
the office. The result has always been good wherever 
destruction of the hair follicles bad not taken place. The 
good effect is brought about in two ways (l) by the direct 
action of light upon the skin and (a) by the absence of the 
accustomed pressure of the hat, interfering as it does with 
the circulation. The many cases of eczema that recover in 
the summer only to reappear to the winter when there is 
less light and the parts are more completely covered, & 
to illustrate that in the radiant energy all about us, nature 
has abundantly provided the means to the end. 

Action of Light Energy VS. Open Air on Granulating 
Wounds. — In advocating the open-air treatment of granu- 
lating wounds open by day. with dressing at night, the 
mechanism of this serotherapy IS attributed by M. Wagner 
to the action of the air which excites the epithelial cells; 
and at the same time, by the desiccation of the wound 
causing the death of the virulent germs which are found 

It is stated by M. Koijime 1 that M, Bloch has given a 
different explanation, to wit, that it is the white light of day 
which invigorates atonic wounds, and which by desiccation, 
forma a pellicle furnishing a protection against the germs 
of the air. The author agrees with llloch in believing that 

'Desiccation by Phototherapy in the Treatment "f Granulating 
Wotrndi. Revue Internationale tTGIectrothcrapic, Jan., 1904. Abst. 
from Press* Mcdieale. 


it is the energy of light which is effective in facilitating the 
healing of wounds exposed to its influence. 

It is also unquestionably the action of the solar light 
which has contributed to the good results noted by Abra- 
hams in skin conditions by sea-bathing. 

In relating his experience as to the beneficial effects of 
sea bathing in some forms of skin diseases, Dr. Robert 
Abrahams 1 attributes the good results to the prolonged im- 
mersion in the salt water, the friction caused by the bump- 
ing of the waves and the rubbing of the sand against the 
surface of the skin, thus removing incrustations and impuri- 
ties and giving freer play to the action of the salt water, and 
to the drying of the residue of the salt water upon the body 
by the sun and air. He loses sight completely of the influ- 
ence of the sunlight and especially the ultra-violet which so 
far as it exists in sunlight at the earth's surface is more in 
evidence at the seashore than anywhere else save at high 
altitudes. Dr. Abrahams tried the effect of sea water con- 
fined in a small space indoors on the same class of cases 
without obtaining any salutary results whatever. 

*New York State Mod. Journal, Jan. 1904. 


Electric Arc Baths. Arrangement of Light Mechanism. Methods 
I Therapeutic Indications. Pulmonary TttbetfCti 
IS, Bronchitis, Bronchial Asthma. Anrcmia. Neurastlu-ni g, 
Locomotor Ataxia and other Nerve Disorders, 

The Electric Arc Bath. 

Electric Arc Mechanisms and Methods of Use. — An ex- 
perience extending over a period of 1 1 years with the 
electric arc a* a therapeutic agent, ImIi in private and clini- 
cal practice, tblished beyond question the writer's 
confidence in its value. During this time it has been in 
almost daily use. Important as the role ol light energy is 
in relation to skin pathology, it is !>y no ntcans confine I to it. 
It has a place in genera] medicine ol equal if not greater im- 
portance. A description of the apparatus and some of the 
results obtained have been embodied in a report on "Electric 
Light as a Diagnostic and Therapeutic Agent,** 1 and "The 
Electric Arc Path, 2 a Clinical Report." as well as in suhse- 
quent eotitrihutioTis to current literature. The results « 1> 
tainei! in the heginning with a somewhat crude arrangement 
<>f an electric arc led to a further elaboration of the appar- 
atus for its application, consisting of the "Cabinet" or 
"Math" described hi the writer's papers above alluded to, and 
also !>v Fmhert de la Touche in the Revue d'fclectrotherapic, 
April and May, 1896. 

translations of (he Amer. BlecttO Therapeutic, April. 1904. 
Journal of the American Medical Association, 1895, 

"Transactions of the American Electro-Therapeutic V 
i8g& N V Medical Journal, J \, tSog. 'The 

Electric Arc Bath," by Margaret A Cleaves, M.D, 


A description not only of this cabinet, but of the various 
arrangements of arc lamps springing into use, following 
upon a presentation of the physics of light and especially of 
the electric arc may help each reader to an elucidation of the 
question as to the simplest and most advantageous arrange- 
ment of electric arc mechanisms for therapeutic purposes, 
the one capable of securing the best results and, at the same 
time, of being operated at a minimum of time, energy, and 
expense. In discussing the subject of light baths, too great 
care cannot be taken to discriminate as to the character of 
light used, for only in this way can scientific progress be 
made and accurate conclusions be reached. The electric arc 
by reason of its physical properties offers advantages not 
possessed in the same degree by any other source of light. 

In the electric arc there is to be had a miniature sun com- 
parable for therapeutic purposes in every respect to the 
radiant energy from the sun and for purposes of localization, 
when tissue reaction is desired as in skin conditions, it is a 
source of the most intense chemical activity or ultra-violet 
light, superior to sunlight at the surface of the earth. 

When sunlight is obtainable it is to be preferred over 
any source of artificial light for the therapeutic uses of light 
energy in general conditions. For. it is not only the radiant 
energies of the sun which are active, but the fresh air as 
well. The electric arc whether with carbon, carbon and 
iron, or iron electrodes only, is very rich in the short high 
frequencies or ultra-violet frequencies, and therefore is to be 
preferred where an intensely chemical energy is necessary, as 
in skin conditions. No matter if the sun is available, the arc 
is the better source of light energy for skin localization. 

For the use of light energy in general medicine, however, 
the indications are equally well met by means of sunlight. 
Rut there are many days in the winter season, especially in 
all northern climes, when the sun does not shine, when the 
need of the patient, suffering from anaemia, malnutrition, 
phthisis, bronchitis, tuberculosis pulmonalis, etc., for sun- 
shine is imperative. This is true of crowded centres, such 



ab- New York. London and Chicago, Cor example* where by 
11 pf (lie narrow streets and tall buildings, a considera- 
ble proportion of the population are obliged to live in rooms. 
apartments, houseti even, into which die sun never falls, or 
but to a limited extent. There is no opportunity of flooding 
their hut wiili tlu Btm's energies the whole range 

of the spectrum active at the surface of the earth, than which 
no better hygienic or sanitary influence 

These conditions are not only true of the extremely p< 
but of people in comfortable circumstances as well, in the 
larger cities. There are also from f\\c to six months of the 
when the sun is obscured often and for days at a time. 
During these periods every one suffers from the lack of its 
beneficent influence and conditions are engendered unfa- 
vorable to health. But the loss, though temporary, of radiant 
energy t falls most severely upon those who are handicapped 
by disease. Therefore radiant energy baths should be the 
logical outcome Of this need, and form a part of the equip- 
ment of the physician, who by every rational means in his 
power endeavors not only to combat, but to prevent disease. 
The electric arc as an artificial source of radiant energy 
is available over a considerable extent of the country by rea- 
son of the fact that it is very extensively used for the pur- 
poses of street illumination. It is not difficult of manipula- 
tion, and cabinets or rooms for its use are easily and com- 
paratively inexpensively constructed. 

Physically, the arc, as has been stated, is comparable 
to the sun as a source of energy. l T nlike the incandescent 
light bath, it is not a heat bath. Tn fact, the heating effect 
is subordinate to the chemical effect. The effect of the elec 
trie arc bath is not confined to the action of high frequency 
waves alone, the low frequency waves as well as the ozone 
which is generated, play an important part in nutritive 
change. From the administration of an electric arc bath 
there is obtained an action upon the skin, the patient experi- 
ences a pleasant and slightly prickly sensation. There is 
produced, even from a short exposure, upon the ^kin of 


some patients a slight erythema, while with others there is 
but little such effect even from long exposures. The face 
assumes a normal rosy coloring and an appearance of re- 
freshment and repose on emerging from the bath is always 
observed. From the administration of the electric arc bath 
the author has noted the establishment of circulatory 
changes with a uniform regulation of the heart's action, as 
evidenced by improved volume and slower pulse rate, the 
augmentation of the temperature, increased activity of the 
skin, fuller and slower respiration, gradually increased 
respiratory capacity, and diminished irritability of the mu- 
cous membrane in tuberculous, bronchitic or asthmatic 
patients. There is also lessened discharge in those patients 
suffering from catarrhal conditions of the nasal passages. 
In diseases of the respiratory system, a soothing effect upon 
the mucous membranes is always experienced, while cough 
and expectoration are diminished. 

Finsen 1 first published his observations upon the stimu- 
lating action of light in 1895. At the same time he pointed 
out that the chemical rays might be useful in the treatment 
of disease. At that time he did not have in mind the use 
of concentrated light, which has since made his name famous, 
but the use of general light baths, that is, the exposure of 
the whole body to the chemical rays of light. These he has 
also used, and speaks of them always as chemical light baths. 
By them is to be understood a bath of the same character 
as first used by the author in 1893, reported to the American 
Electro-Therapeutic Association in 1894, and in a more per- 
fected form in 1895. A description of this bath with a 
report of cases treated and results obtained was presented 
to the American Elect ro-Therapeutic Association at its 
eighth annual meeting in Buffalo, 1898, and was published 
in the Transactions of the same year. 

Both reports were also published in the current Medical 

'Journal of Physical Therapeutics, Oct., 1900. A note on Light 
Baths, N. R. Finsen. 



Chemical light baths have a very deckled action upon 
the skin. This was indicated by ihc results obtained from 
the use of the electric arc hath in the authors experience, 
but it has been fully established by the experimental work 
of F in sen. 

The dilatation of the capillaries and blood vessels of the 
skin by the action of the chemical frequencies is not an alto- 
gether acute or rapid process, but is one of long duration, 
reason, therefore, of a light bath there is established a 
dilation of the cutaneous vessels, which determines a more 
active supply of blood thereto. This in turn Unquestionably 
influences favorable nutrition, enabling the skin to better 
perform its function. But this action is not alone confined to 
the skin. It penetrates farther, and is much more far-reach- 
ing in its beneficent influence. 

Description of Arc Light Cabinet. — The cabinet used by 
the author for the past 9 years is 6 feet long, j! feet wide, 
and 7 feet high, built in the corner of one of (he office rooms. 
It is entirely closed in, save for an observation Window, 
which can also be utilized for the admission of fresh air, if 
desired. It is lined with zinc throughout in order to pre- 
vent any danger of fire from a fragment of burning car- 
bon. This zinc lining is painted white, and finished with 
white enamel in order to afford the best possible reflecting 
surface for the light. The lamps, two in number, are sus- 
pended Ode at each end of the cabinet, with a shield of glass 
directly underneath to prevent particles of carbon falling 
Upon the patient The light of the arc is projected toward 
1 lie patient's body by means of reflectors placed back of each 
arc. These reflectors or mirrors are of glass, silvered at 
the back and concave. By their use the operator is enabled 
to direct the beam of light at will Upon the pari of the body 
where it is desired t<> secure the actum of the greatest in- 
tensity of the light energy. 

The cabinet contains an ordinary wire-mattress cot. which 
ide tip as a bed with fresh linen for each patient, and 
Upon which the patient reclines. 


In the author's office the current is taken from the Edi- 
son incandescent mains at 1 10 volts pressure, and each lamp 
takes about 10 amperes at 50 volts, the remainder l>eing 
consumed in the rheostat. 

At the New York Electro-Therapeutic Clinic the lamps 
were on the Thomson-Houston alternating-current mains of 
104 volts, and each lamp took 9 amperes at 48 volts, the 
remaining 8 volts being consumed in the rheostat. 

Both equipments have given satisfaction, but the con- 
tinuous-current arc lamps have been somewhat less difficult 
of adjustment, and, therefore, have required less care. 1 

As the patient lies at rest in the bath he is bathed in a 
flood of light emanating from sources of 4,000 total normal 
candle-power (the arcs of 2,000 candle-power each). While 
the patient's entire nude body should be exposed to the 
action of the light energy, exposures arc sometimes made 
with only a partial undressing. The eves arc protected 
from the intense light by means of colored glasses, and, 
if desired, the face and hands may also be protected to 
prevent the tanning effects of the light or an artificial sun- 

All patients, but especially phthisical and bronchial 
patients, arc directed to breathe in deeply and fully while 
lying in the bath. 

Practically the same arrangement, copied from the 
writer's, is in use by physicians in various parts of the 
United States. It was also copied in all essential points 
by Tmbert de la Touchc of Lyons.- In an article in the 
Revue Internationale d'ftlectrotherapie, April and May. 
1896, he described the author's cabinet, and also his own 
modification, which consisted in placing the carbons at an 
angle, probably 45". In this way the crater of the positive 

'The case with which hoth continuous and alternating current 
arcs may he operated is a matter of (1 ) a knowledge of the mechan- 
ism and (2) experience in handling lliem. 

2 A Novel Application in Therapeutics hy Iinhert de la Touchc. 
France, filcctrophototherapie or Bath hy Light. Revue Internation- 
ale d'filcctrotherapic, April and May, 1896. 



carbon served as a reflector enabling' him to dispense with 
the reflector 'is used by the author, and to secure more of 
the energy of the light of the arc proper, hi the author's 
cabinet hut one patldlt can be treated at a time, and it is not, 
therefore, bo desirable in dispensary practice, where it is 
necessary to care for a number of patients simultaneously, 

as a room arranged wuii one or more powerful arcs, 80 to 

100 amperes suspended from the ceiling, and at the same 
distance from the floor as in the cabinet just described, Le. t 
6i feet 

The size of the room may vary according to the number 
of patients to be treated, or the facilities at the operator's 
command It may be divided by screens or partitions as is 
necessary, and the couches can be placed radially from the 
centre, and in an inclined position looking toward the light. 
This is the arrangement used by I ; inseu in the administra- 
tion of electric arc Intbs, the following description of which 
is from his pen f 

Finsen's Light Baths. — These consist of a circular room 
aboul 37 feet ( 12 metres) across, from the ceiling in which 
are suspended two powerful arcs, EOO amperes each, at a dis- 
tance of a little over 6 feet (2 metres) from the floor. The 
room space is divided by means of partitions extending 
radially from tbe centre, which secures the necessary privacy. 
In the individual small rooms thus obtained, beds are placed 
in an inclined position. Upon these beds, with the body 
entirely divested of clothing) the patients lie, exposed to the 
radiant energies of the arc. These baths, as has been 
stated, are in no sense heat baths, and as a matter of fact. 
the temperature is so low that it is necessary to warm the 
rooms for the comfort of the patients; yet, notwithstanding 
the lowness of the temperature, the chemical action upon the 
skin b quite as strong as sunlight. A pleasant warming and 
tingling of the skin follows their use. The length ot ex- 
posure varies from 10 minutes to an hour. In the author's 

journal Physical Therapeutics, Oct., igoa 


cabinet 1 the exposures are from 15 to 45 minutes. Different 
patients differ in their susceptibility to the action of the 
chemical frequencies upon the skin. A very pronounced 
erythema in the more susceptible subjects may be produced 
in 10 minutes ; in others, there may be only a slight redden- 
ing after an hour's exposure. 

The electric arc, either in the form of a cabinet bath, 
or by projecting the beam of light on the part as with the 
marine searchlight, has given excellent results in the treat- 
ment of muscular rheumatism and the different forms of 

With cots of ordinary height, the distance of the patient 
from the arc would be the same as in the author's cabinet, 
i.e., 4 feet. Given lamps of the same electric power, and, 
therefore, capable of producing the same quantity of light, 
there will be approximately the same total radiant energy 
emitted in each instance, i.e., in the small cabinet or the large 
room, but the energy for each square inch of surface ex- 
posed to the light activities will be very much greater in the 
smaller space, owing to the reflection of light from the 
walls Therefore, if the greater expenditure of energy As 
not desired, lamps of smaller amperage can be used which 
will minimize the expense for current. On the other hand, 
when indicated by the pathologic condition, the greater in- 
tensity per square inch of surface exposed would produce 
better therapeutic results. From the results obtained there 
is every reason to believe that two TO-ampere lamps in series 
would produce sufficient energy for so limited space. There 
is, however, no objection to using arcs of higher amperage 
if the operator desires, bearing in mind always that the 
amount of light emitted by the unit area is practically the 
same. To increase the amount of light emitted, the size of 
the crater must be increased in order to provide a larger unit 
of area. 

There are also quadrangular cabinets, wjth the arcs 
fitted in each corner. In these the patient sits w f ith his head 

transactions American Electro-Therapeutic Association, 1898. 



outside as in an incandescent hath. Such cabinets are used 
in Germany, and Freimd refers to than as the are light 
enclosed hath of Kellogg. The lamp mechanism is bo ar- 
ranged that the light energy can be thrown both upward 
and downward, and directed upon any part of the patient's 
body at will. Arrangements are made in these cabinet 
the introduction of colored glass filters, according as to 
whether it is desired to use the visible chemical energy of 
the arc, blue glass, or to minimize the heat by the use of red 

Freund objects to the use of reflectors to intensify the 
light, on the ground that "hum-blisters" are liable to be 
formed on the part of the skin to which the concentrated 
arc light energy falls. The author has had no such trouble 
with 25-ampere arcs where the energy has been projected 
Upon a part by means of a Mangin mirror. Another objec- 
tion which he offers, accrediting the thought to Strehel. does 
not exist in fact, viz., the formation of noxious gaseous com- 
pounds (acetylene and other compounds of carbon 'tnd 
hydrogen), which lie says are not only absorbed by the skin, 
but alsi> escaping at the neck opening, may penetrate the 
patient's air passages. The author has fully considered 
under the physics of the electric are the nature of the gases 
given off by it when in activity, from the physical chemist's 
point of view. From the investigation of the subject there 
is nothing to lend color to the thought that such gases gen- 
erated during the activity of the arc exist in sufficient quanti- 
ties to exert a deleterious action during the time the patient 
is exposed to their influence. 

The reader is referred in this connection to the chapter 
on Physics of Light Energy, in which the nature of the g 
given off by the active electric arc is fully considered. 

The enclosed cabinet described in these pages has been 
continuously in use for 9 years. Exposures have been 
made froni 15 to 45 minutes in length, to tubercular, asth- 
matic, bronchial, amen lie. convalescing grippe and broncho- 
pneumonia, neurasthenic, neuritie, etc., patients not only 


without bad effect but always with good and with, as has 
been stated, so immediate and favorable an effect upon 
cough and expectoration, that it has always been felt that 
there was effective some form of energy of a powerful 
oxidizing character other than the light energy. Ozone 
which from the most careful experiments is shown to be 
present, but not in large quantities, would produce this 
effect in respiratory conditions. The nitrous oxide given off 
in larger quantities does not seem to act deleteriously, nor 
does it when generated by the disruptive discharge of influ- 
ence machines as they are used. The air of the rooms occu- 
pied by the latter as well as the air of the arc light cabinet, is 
deliciously pure, having the same odor and freshness as at 
the seashore or mountain top. 

It should be noted, however, that the cabinet described is 
really a small room with large cubic foot space, and after 
these years of use, the author has not seen fit to change it in 
any particular save to lower the lamp mechanism a few 
inches. The window for ventilation should preferably be 
placed in the upper part of the enclosing side or end, as the 
impure air rises. If desired two windows may be provided, a 
lower one for observation and the ingress of pure air, and 
the upper one for the escape of impure air. In practice this 
has not been found necessary. Just here it may be well to 
say that the upper carbon should be positive, in order that 
the crater may serve as a reflector and the light energy be 
directed downward upon the superficies of the body. The 
placing of the carbons at an angle, as was done by Imbert de 
la Touche in his modification of the author's cabinet, enables 
the direction of the maximum light energy to the superficies 
of the exposed body. 

Single arcs of from 10 to 25 amperes are also in use in 
the offices of physicians throughout the country and the 
effect of the light energy from these is heightened by the use 
of parabolic reflectors. In this way the light which would 
otherwise be radiated upward, is reflected downward upon 
the patient. 


The small enclosed rectangular cabinet described by 
Kellogg and used in Germany, the author does not advise for 
arc light baths. The light energy, as well as the other 
activities of the arc, serves the physician's purpose better 
when diffused in larger cubic foot area. These cabinets as 
constructed in Germany arc usually a combination of an in- 
candescent and arc light bath, arranged so that the energy 
of both can be used at will, or either the one or the other 

This combination is not advised. The therapeutic indi- 
cations for the incandescent light bath, which have been 
fully considered, are different from those of the arc, 
although they touch at points. But to secure the best results, 
these cabinets should be constructed on different lines as has 
beefl pointed out. This is not possible where one enclosing 
cabin* t serves both purposes. 

In the use of these various arrangements the patient 
occupies a recumbent or sitting position, and is, as has been 
stated, either wholly or partially divested of clothing. 

In the writer's cabinet, and also in the room used by 
Finsen, beds are provided which make it possible for the 
patient by reason of the reclining position and protection 
from currents of air from underneath, to be entirely nude 
without chill or discomfort. This is not possible in the use 
of the marine searchlight, for example, unless the beam 
therefrom be projected into a cabinet, for by reason of the 
size of the beam and of currents of air only a partial ex- 
posure can be made. Nor is it desirable that all the patients 
for whom these baths are indicated should occupy a sitting 


It is only necessary to keep in mind the condition of 
patients for whom treatment by means of an electric arc 
bath is indicated, to appreciate how essential it is. first, that 
the entire body be exposed to the action of light, and second, 
that it be administered so as to minimize the patient's dis- 
comfort, and avoid any danger of chill. 

But while no better reasons * kisI than the well-being of 


the patient and the exposure of the entire body to the bene- 
ficent influence of this bath of radiant energy, there are 
reasons dependent upon the physical laws governing light 
why one method of application is better than the other. 
Scientific progress will be much more rapid and sure if at 
the outset there can be secured to the physician, who may 
desire to avail himself of light as a therapeutic measure, an 
arrangement of lamp mechanisms capable of securing the 
maximum benefit with the minimum expenditure of time and 
electric energy. 

With the arc suspended above the patient as in the 
author's cabinet, and also in Finsen's room, where the arc 
is suspended from the ceiling and couches arranged radially 
around it, the light falls perpendicularly upon the patient. 
This is correct according to physical laws. In this way the 
whole of the crater light and the light of the arc are thrown 
down upon the patient's nude body, thereby securing an 
irradiation of the highest chemical activity compatible with 
the amperage of the arcs used. 

The field of usefulness of these artificial light baths 
energized by electric arcs is as broad as the domain of 
medicine itself. 

In the writer's personal experience the non-concentrated 
light energy of the carbon electric arc has been found of 
great value, in both primary and secondary anaemias, mal- 
nutrition, neurasthenia, in neuritis and neuralgias, in tuber- 
culosis of the bowels, in sprains and contusions, in eczema, 
seborrhceic eczema with loss of hair, psoriasis and in acne, 
as well as in respiratory diseases. In no one condition is 
it of greater value than in tuberculosis of the lungs. 

The Electric Arc in Tuberculosis. 

No countries suffer in the same proportion from tubercu- 
losis pulmonalis as the British Isles. This, without doubt. 
is largely due to the absence of sunshine over prolonged 
periods of time, an untoward physical condition which is 
still further contributed to by the fog and dampness. In- 


stead of the organism being battled in sunlight for the most 
part, there are consecutive weeks and months in which the 
sun rarely shines. The absence of the sun's rays inter 
with all the functions of the economy. 

There can be no question lint that the living organism is 
to be regarded as an energ\ transformer, and under normal 
conditions it would seem to functionate as a radiant en 
transformer as well. By the absence of the complex of 
lengths from the sun, absolutely essential to its well h- 
depressed and disordered function obtains. The influent 

the chemical frequencies upon tin u i stream, and e 

daily upon its oxygenating power, is in abeyance; mal-nutri- 
ti> n result* and the micro-organisms find a fit habitat for 
their development. Especially is this true of the tuberculosis 
bacillus. Patients suffering from tuberculosis are sent where ? 
i land <d sunshine. When a climatic change becomes 
necessary the place selected, whether by the set ^>r inland, 
whether of ordinary or high altitude, is always a place where 
the sun shines, where for maximum periods of time the 
patient is under Its beneficent influence. Not every patient 
can avail himself Of herself of such a change. It nun be 
absolutely imperative to remain at one's post of duty, win * 
ever that may be* no malter how grave the impending dan- 
ger. Work and a degree of ill health are not by any means 
incompatible, and the patient may so order his life as to meet 
the daily duties and at the same time have the treatment 
tending to a restoration to the normal. 

It is possible in almost ever) city and village throughout 
the COtintry, to have the means of subjecting the patient to 
the action of artificial sunlight, during the season whei 
posurc of the nude body to sunlight is impracticable 
because of the cold and the many sunless days of the winter 
solstice. This lack of sunshine may not only be true of the 
winter months, but often characterizes long periods of time 
during the summer solstice as well. During days of wind, 
damp and cloud, tubercular patients sutler very greatly, and 
the disease progresses more rapidly. 


Climatically Arizona very nearly fulfils these conditions, 
and, therefore, offers the very best conditions for patients 
suffering from tuberculosis. The territory is largely an ex- 
tensive plateau, hundreds of miles from any large body of 
water, situated between the two greatest ranges of the 
Rocky Mountains, traversed by mountain ranges and sur- 
rounded for several hundreds of miles on every side by 
sandy deserts. The even temperature and dryness are 
Arizona's chief claim to merit. The dryness means sunshine 
— the humidity in the air as reported by the U. S. Weather 
Bureau at Phcenix was on several occasions in July, 1900, as 
low as 1%. There is the greatest percentage of sunshine at 
Phoenix, Arizona, reported by any U. S. Weather Bureau 
office. In November of 1900 the average daily sunshine for 
that month was 9 hours, 12 minutes. Davos Platz, 
prominent in Kurope for its sunshine, had but 4 hours 
and 12 minutes average for the same month. A very 
noticeable effect of the dry air is the great diminution in the 
amount of sputum in those cases in which there is exces- 
sive bronchia] catarrh associated with the tubercular lesion. 

This is an atmosphere comparable in temperature, dry- 
ness and radiancy to that of an electric arc bath, as was 
pointed out by the author in i&jH. 1 who likened the condi- 
tions of the arc light bath to those of a clear dry sunlit day, 
and these are essential features of a climate for tuberculosis 
which it would be well to imitate artificially whenever pos- 

In an electric arc bath there are no elements of depres- 
sion, as in exposure to hot air. for it is not a heat bath. Tt 
is only gently warmed, and from it there is obtained a sen- 
sation of life and vitality. The chemical activities, which are 
cold, alone act upon tubercular lesions. This is proven by 
actual clinical observations, not only in tubercular diseases 
of the skin, but in tuberculosis pulmonalis, thereby showing 
that they are the effective rates of the vibrational activity 

'The Electric Arc Bath. Am. E. T., Sept., 1898. 



or frequencies of light energy. By cold light must always 
he understood the frequencies <>t intense chemical activity, — 
blue, indigo, violet ami ultra- violet. In a complex of all the 
frequencies oi the electric arc, also in the ionization of the 
air by its action and the production of its gases, the author 
believes that there is to be had a physical condition compar- 
able to sunlight and fresh air. Its use cannot be continued 
over indefinite periods of time, nor for thai matter can the 
same class of cases he exposed indefinitely to the action of 
sunlight, Care must W taken In both instances, An exposure 
to sunlightj and likewise to an arc light, means an expendi- 
ture of energy within the tissues, and no mechanism, whether 
the living organism or a high frequency transformer, for 
example, can lake care of more energy, transform it in other 
words, than it is built or wound for. If there is loo great 
an expenditure of light energies, either from too intense 
exposures or over too prolonged periods of time, the organ- 
ism will suffer. 

The opinion appears to he widespread that to use light 
therapeutically demands expensive apparatus, prolonged ex- 
posures, a large staff of nurses and great expense. Willard 
places the expense of operating a Fifteen apparatus at 
$3,000 a year, and in the expense finds an objection to the 
H8e <d' light in the treatment of tuberculosis of hones and 
joints. In other words, the popular impression seems to be 
that an equipment which excludes all the energies of the arc. 
save the short and high frequency rates of the chemical end 
of the spectrum, especially a source very rich in ultra-violet 
frequencies, is called for. 

The prominence given to phototherapy by the brilliant 
work of Finsen, \n lupus vulgaris especially, is no doubt 
largely responsible for tin- opinion. Bui it does not neces- 
sarily follow that even in the treatment of lupus vulgaris 
and other skin lesions, 50 expensive an outfit initially, nor 
such tremendous consumption of current is necessary, 

\ clinical experience with light ;i^ a therapeutic measure 
since 1893, has demonstrated to the writer's satisfaction that 


such is not the case in general conditions where applications 
of light diffused in a cabinet is desired, or in the case of 
strictly local lesions where concentrated and condensed in- 
tensely chemical light energy is indicated. 

The value of sunshine in the treatment of tuberculosis, 
whether of the lungs, bones, joints or glands, and also in 
bronchitis, asthma, convalescence from grippe and broncho- 
pneumonia, for example, is recognized and utilized just so 
far as is possible in combating such conditions. 

In the electric bath there is to be had all the radiant 
energy characteristic of sunshine, not only in a more con- 
centrated, and, therefore, more active form, but a spectrum 
richer in ultra-violet frequencies than sunlight because of 
the absorption of these in transit from the sun. It is also a 
source of radiant energy which is available at all times, no 
matter what the weather conditions. 

In the crowded cities where the greatest need exists for 
radiant energy to meet the needs of tuberculous patients, the 
electric arc is always available, not only at all seasons, but 
at all hours of the day or night. Cabinets for this purpose 
cannot only be equipped but operated at a reasonable ex- 
pense, and from their use an expenditure of energy similar 
in physical character to an expenditure of energy of solar 
light be obtained. 

The inhibitory power of sunlight upon the growth of 
tubercle bacilli was established some years ago. The same 
is true of electric light. In the laboratory this inhibitory 
action of electric light is much more powerful than that of 
sunlight, and in the especially equipped rooms or cabinets in 
a physician's office this is equally true. The claim is made 
that this is not true of electric light in practice. Xo doubt 
under the latter conditions it is influenced by the arrange- 
ment of mechanisms for light administration, the amperage, 
and the method of their employment. This in no sense re- 
fers to a destructive action upon the bacilli within the tissues. 

With the author, Freund believes that for an effect upon 
the deeper tissues longer and slower frequencies than the 



ultra-violet rays are necessary. Laboratory experiments 
with the chemically active light energy are made upon plate 
cultures. In practice, the conditions are different. The 
bacilli are located deep in the t nd the ultra- violet rays 

must first pass through a relatively thick absorbing layer 
before they reach the bacteria. To secure such an effect, the 
intensity of the ultra-violet rays must be very great, the 
exposure very long, and it is quite within belief that the 
superficial layers of the skin would be severely injured. 
The work of Bernard and Morgan 1 seems to have established 
lusivelv that in bactericidal effect upon plate cul- 
as well as on the power to excite tissue reaction, the 
ultra-violet frequencies are the active ones. 

That other dements of concentrated light, of larger wave 
lengths, that is, longer, dower and of greater amplitude, 
greater penetrancy, and which exert no such injurious 
effect upon the li have a curative effect is not only 

• t' bdief, an«l capable of rational demonstration, but has 
been established clinically. 

It! tuctl conditions as tuberculosis pulmonale For exam- 
ple, the indications arc not only to be met by an applicati< 
concentrated light energy over the lung lesion, but the im- 
poverished blood musi be fed, nutrition must be improved 
and the vital resistance increased. To this end it is necessary 
that the entire organism should he subjected to the action ««f 
hght energy. T h er efore it is nol necessary t«> concentrate 
ami condense the chemically active energy as in the treat* 
oi a lupus patch or nodule The indications are best 
met by distributing all the energy uniformly in the rooms or 
the cabinets arranged for this purpose and exposing the 
entire body fcO all oi tl trie arc spectrum 

just as in the case of a sun bath. In the latter it is recog- 
nized that the effective energy is a complex of the frequen- 
cies of the solar spectrum. In this way. the more intense 
chemically active frequencies are able to exercise their 

The Physical Factor* in Phototherapy. J. E. Bernard 
di- R. AAorgsn British Med. Journal, Nov. 14, rg 


especial function or role in the maintenance of health, or in 
combating disease in common with the remaining energy of 
the spectrum without any clanger of untoward skin effects 
such as would obtain from the same energy when concen- 
trated and condensed. 

The indication here is not for a light energy capable of 
exciting superficial tissue reaction, but for a light energy of 
great penetrancy capable of the most profound action upon 
the blood in order that its normal function as the great oxi- 
dizer may be accentuated. 

To this end the visible frequencies of great chemical 
energy, the blue, indigo and violet, are needed, but it has 
always been the author's practice to use the entire energy 
of the arc. The function of the former is therefore shared 
by the latter, but the mass of experimental and clinical evi- 
dence as well as the absorption spectrum of oxyhemoglobin 
point to the former as the fundamentally active frequencies 
upon the blood. 

The action of light in tuberculosis is so evident that it 
does not even admit of discussion. A glance at its clinical 
history, at the factors that favor its development and the 
climatical conditions favorable to either recovery or im- 
provement, bears out the imperative necessity for light 
energy in this disease — not alone, but in conjunction with 
the best hygiene and sanitation, good feeding and exercise 
according to the individual's ability. Fresh air, sunshine, 
altitude according to the individual patient, but preferably 
high, conjoined with the above are universally recognized 
as of more value in combating tuberculosis than all the drugs 
of the materia medica. 

De Renzi 1 who was one of the earliest to study the effect 
of sunshine on disease, undertook to answer the inquiry as 
regards tuberculosis by inoculating guinea pigs with tuber- 
culous material. It is very evident from these experiments 
that sunshine assisted these animals materially in combat- 

*De Renzi: Nature. 1894. 



ing the infection, as the individuals cot off from the sun's 
vdccumbed much more quickly than those exposed to 
them. Some of the animals were kept in glass boxes ex- 
posed to the direct action of the sun s rays tor from 5 
to 6 hours daily ; while others were placed in the sunshine 
also, but instead of glass, opaque wooden boxes were used. 
De Renzi found that the inoculated pigs in the glass boxes, 
receiving the maximum amount of sunshine, died after 24, 
yj, 52 and 89 <lavs respectively, while those in the opaque 
wooden boxes died after 20, 25, 26 and 41 days respectively. 

The action of light on tubercle bacilli without the living 

organism has been the subject of numerous experiments and 

it is well known that they die rapidly in a sunny atmosphere. 

Koch showed that tubercle bacilli were killed b] rc to 

ght. Later 1 ric arc was used for the same pur- 

because of its richness in the chemical frequencies, 

ally the ultra-violet and was found to act even more 


Drs, W, C Mitchell and IL C Crouch 1 of Denver. Col- 
orado, made some experiments on tuberculosis sputum in 
reference to the great degree of immunity against tut>erculo- 
1 joyed by those living .it high altitudes. They deposited 
sputum from tul> patients, as tree as possible from 

mixed infection, on sterilized soil and 1 it to sunlight 

from - ; hours, 6 hours ctail ea pigs were then 

ulated at ntrol-pigs injected at once 

died in 20 days, ( >f those animals inoculated with sputum 
exposed more than 35 hours none died. Pigs inoculated 
with sputum exposed Only for 35 hours died of tuberculosis, 
but from the lesions, the infection in those animals was 
thought to have been due to inhalation. After exposure of 
from OOe to 25 hours, the sputum killed the pigs in all but 
one case, 1»v tuberculosis, that one alone dying of sepsis. 
None of the animals infected with sputum which bad been 
jjj hours died of tuberculosis. Opportunity 

Tin! ;.■ [edict! Journal, Jnnu it, 1898, 


is offered, however, in that period of time for desiccation 
of the sputum and infection of others. They reasoned from 
these experiments that the dryness of the atmosphere pre- 
venting the growth of the bacilli, as well as the sunshine, 
was therefore a factor in determining the good effects af the 
Colorado climate especially in tul>erculosis ; and that this 
was added to by the high altitude, increasing as it did the 
blood supply to the lungs and improving the nutrition of the 

Baradat 1 likewise finds that light enriches and nourishes 
the blood, produces a great reserve of energy, stimulates the 
nerve ends and vivifies the nerves: it acts upon the skin, 
accelerates its action and is able to renew the same. In his 
opinion, light attacks the bacilli directly and by its action, 
the condition of the tuberculosis soil is ameliorated and 
renewed. In the article quoted, he reports two cases that had 
been treated for 6 weeks ; after 6 days' treatment the night 
sweats ceased, the cough diminished despite unfavorable 
weather and defective care, and the num1)er of bacilli de- 

Dr. Albert E. Sterne, 2 of Indianapolis, Indiana, also finds 
the electric arc valuable in tuberculosis. Tie finds its use as 
rational as sunlight itself and that the chemical frequencies 
from it possess a decomposing, but at the same time, recon- 
structive molecular action upon the body tissues mainly 
upon the blood elements. He used in addition to the great 
quantity of light from powerful voltaic arcs, free ozone de- 
veloped from an especial ozonating apparatus, as described 
under alternating-current light mechanisms. 

FrcudenthaF has used electric light in tuberculosis for a 
number of years, having used it since 1889 in tuberculous 
laryngitis. In that year he first exposed the larynx to the 
light from an incandescent lamp of very low candle-power 

'Zcitschr. fur Tnbercitlosc. mid Heilstaettcnwesen. TO03, Bd. V. f 
Heft 1. 

"Paper read before the Mi-^iVippi Valley Med Ass., Kansas 
City, Mo.. 1902. 

'Freudenthal : N. V. Med. Journal. July u. 190.2. 



hut for the purpose of transiUumining the laryngeal region 
as an aid to diagnosis, Eic was led to investigate the mat- 
ter and also to continue its use by the statement of a patient 
for whom at first light was used as a diagnostic aid. It was 
then. discontinued and the treatment carried on, along the 
usual line- I toe day the patient asked why he did not use 
that light treatment any more, living that she always felt 
hetter from its use. From that time he has used it uninter- 
ruptedly iti this condition. In the more recent years he has 
used an electric arc in preference as it is the hetter source of 
light energy for tuberculosis puhnonalis and even for 
laryngeal troubles. 

lie has found that the marine searchlight mechanism 
f«ec Pig, 21) stands him in good stead. In the beginning 
of the treatment for some of his cases he uses the blue glass 
Screen, sin iwu in the same figure, to eliminate the frequencies 
below the blue on account of the heat, As a rule he prefers 
the use of all the frequencies of the arc, as pointed out by the 
author. He attributes some bactericidal power to the red 
h> quendes even. Thai they are chemical to a degree is true, 
according to the nature of the body or substance upon which 
they fall, and it is possible that they may have some bacteri- 
cidal power, although more recent work places the bacteri- 
cidal rays in the middle third of the ultra-violet region. In 
utilizing the marine searchlight as a source of light en- 
Freudenthal uses the parallel rays, and directs the patient to 
turn the body around in order to prevent any undue heat 
effect . He also keeps on hand pieces of linen on ice, with 
which the exposed parts are quickly washed as soon as they 
become hot. The distressing symptom of dysphagia from 
which patients with tuberculosis of the larynx suffer, has 
yielded to a greater or less extent from the use of light in 
his hands. In a case in which laryngeal stenosis had oc- 
curred, tracheotomy had been performed. Afterward upon 
examination it was found that the epiglottis covered almost 
the entire entrance of the larynx. lie had also tuberculosis 
of both apices, though not far advanced and suffered from 


excruciating pains in the larynx, which no drug could re- 
lieve. As a dernier resort Freudcnthal tried the electric 
light for him, which was the only thing that afforded him 
some relief. At least he was able to take some food. 

In the light treatment of tuberculosis, it is not that in 
the intense chemical frequencies of light there is an energy 
capable of bactericidal effect primarily, but that there is an 
energy w r hich judiciously expended tends to the active oxy- 
genation of the blood, improved metabolism and consequent 
nutrition. In other words, every application within the 
recognized limits of the best therapeutic management of a 
given case increases physiologic resistance which results 
in the fortification of the individual for the conflict. The 
destruction of the enemy within the organism follows in 
the natural order of things in 2 ways, ( 1 ) by the improved 
nutrition and vital energy, and (2) by the ability of the 
rhythmic vibrational activity of the higher chemical frequen- 
cies to unduly agitate, shake up or worry the micro-organism 
until it delivers up its energy or oxygen. Hut it cannot be 
too strongly stated that the fortification of the individual 
is by far the most important consideration, and to that end 
every effort should be bent, not alone in the exhibition of 
light energy, but in attention to every detail of hygiene and 
sanitation, fresh air. suitable exercise, good nutritious food, 
and sunny and well ventilated rooms. No matter what the 
special means used to establish a cure in tuberculosis, or for 
that matter in any disease, no known physical law should be 
disregarded, nor the use of any accredited measure. Hut 
there is no class of cases where the skilful use of light energy 
is so imj>erative or of such great avail as in tuberculosis. 
The hygiene, sanitation, climatology, prophylaxis also of 
tuberculosis have come in the l&st years to be above criticism, 
but the therapeutic management, despite the use of all the 
accredited physical agents, will fall short of what it should 
be until light energy is skilfully used in its treatment, not 
only in institutions but private practice ps well. It does not 
matter, from the author's point of view, that the most in- 



tense chemical energy does not penetrate into the deeper 
structures. The very fact that they are ahsorhed by the 

first thick layers of bl I vessels of the thoracic wall- 

example, does not militate against their usefulness. The 
tiniest mountain rivulet, the merest thread of a stream in its 
steady onward Bow toward the valley is a source of energy 
which helps eventually to swell the tremendous flow of 
water through the mountain canon. Equally true is it that 
the absorption of these very refractive frequencies by the 
oxygen-carrying corpuscle of the superficial blond vessel 
imparts a stimulus, the influence of which must be felt to the 
Uttermost extent of the circulation :>f the blood- In tuber- 
culosis there is no greater necessity than for perfectly 
genated blood. The increase of red blood corpuscles is asso- 
ciated with an increase of white blood corpuscles, bacilli are 
deprived of their energy, normal tissues are properly fed. 
and degenerated masses are removed through the increased 

The statistics of those experienced in the treatment of 
tuberculosis have shown that in order to obtain favorable 
results the patient must be secured when the disease is in 
the first stage or stage of infiltration. Not only the phy- 
sician, but the general public as well, should recognize the 
necessity of the most earnest efforts when the disease is in 
its incipiencv, and in addition to the hygiene, sanitation and 
climatic conditions, there should be added in every case the 
systematic use of the energies of ( i ) solar light where avail- 
able, and (2) of the electric arc when the former cannot 
be commanded. Reliance upon the results of the sputum 
examination to establish the diagnosis cannot be too strongly 
condemned. It is unquestionably one of the potent factors 
leading to a paucity of favorable results. The fact of the 
presence of bacilli in the sputum, while technically the con- 
clusive proof of the disease, should not be waited for before 
placing the patient under the best conditions from every 
point of view. Both the microscope and the Roentgen ray 
are valuable aids to tin- diagnosis of tuberculosis, but neither 


the one nor the other can take the place of a careful and in- 
telligent physical examination. One. two, or three negative 
sputum examinations are not sufficient evidence in view of 
physical signs, to withhold a diagnosis, and no physician 
should wait until the lungs break down sufficiently for the 
throwing off the tubercle bacilli, to establish the very best 
therapeusis. Were this always done, then an expenditure 
of light energy would hasten the recovery of every such 
patient. This is well illustrated in Case IV. of the 6 cases 
of tuberculosis reported from the author's cases. 

Treatment was first instituted by the author in cases of 
tuberculosis in the spring of 1895 by means of the electric 
arc. 1 

The patient was placed in the arc cabinet previously 
described, exposing at first the anterior surface of the 

By changing the position and lying with the posterior 
part of the body uppermost every square inch of skin sur- 
face was exposed to all the radiant energies of the arc, and 
at the same time to the gases given off by it, which exert a 
favorable influence. A part of these cases were treated at 
the author's clinic (The New York Electro-Therapeutic 
Clinic and Dispensary), and a part in the private office. At 
the former alternating-current arcs were used, at the latter 
direct-current arcs. The results obtained indicated that 
the one was as good as the other. Under the physics 
of the electric arc it has been stated that theoretically alter- 
nating-current arcs should give off more ozone, as it is sup- 
posed that such ozone as is given off by an electric arc is 
due to the breaking of the arc, and by reason of the alter- 
nating E. M. F. there is a constant make and break of the 
arc, i.e., at every change of sign. 

These exposures were made to the entire nude body for 
from 25 to 45 minutes daily in private practice, and later 

'Transactions of the American Electro-Therapeutic Association, 
1898, New York Med. Journal. Jan. 2$ and Feb. 4, 1899: "The 
Electric Arc Bath," by Margaret A. Cleaves. M.D. 



Ml, as the ease progressed, less frequently. In clinical prac- 
tice 3 treatments pet week were gives on the regular clinic 
days. There was invariably secured by this light bath, 
diminution of cough and expectoration, freer respiration 
with increased respiratory capacity and quickened circula- 
tion. It 1 ; use was always followed by a sense of well being 
and a general appearance of refreshment. Improvement 
the rule in every case, lasting in the incurable cases for 
varying periods of time. A laryngeal ulcer in an advanced 
case of phthisis, winch had defied every effort of skilled 
specialists! promptly healed in 2 weeks* time without any 
local application whatever, even of the light energy, while 
all the Symptoms were ameliorated, and marked nutritional 
gain established. See Case 11. 

Acute Phthsis. — E. ML, a man aged 28 years; married; 
carpenter. January 2$, 1 

Patient presented him-. 1 1 because of cough, with pain 
in chest, following a malarial attack last summer. Now 
has constant cough, muovpurtilent expectoration, night 
sweats, cachexia. 

Inspection; Skin pale and white; emaciated; clavicle and 
ribs Conspicuous; retraction of chest walls, with impairment 
of motion in infraclavicular spaces; heart beat in normal 
position accelerated. 

Palpation : \ oca I fremitus increased at right apex. 

Percussion: Marked dulness over right apex, extending 
[* fifth interspace. 

Auscultation: Broncho-vesicular breathing, sibilant anil 
suberepitant rales over right apex. Increase of v< cal sounds, 
On left side very harsh inspiration and broncho- vesicular 
expiration. Pulse, 100; temperature, 100.2- ; weight, 121 J. 

Treatment : Electric-arc bath ; exposure from 20 to 30 
minutes ; temperature of bath, 90' F. hive treatments given, 
extending over a period of 2 weeks. At second visit "more 
life and energy and fe!t like getting around," before "fdt 
like sitting about"; appetite better; cough diminished. At 
mux of the third visit, further diminution in cough; sputum 



less purulent. At the fourth visit cough was much dimin- 
ished, strength increased, a sense of well-being present. 

Improvement maintained; no night sweats while under 
care, save night following first treatment ; improved color ; 
gain in weight, 2\ pounds. The patient through whom he 
came to the clinic reported, 2 weeks later, continued improve- 
ment, and that he had gone to work again. Subsequent 
history not known. Two specimens of sputum were se- 
cured and examined, but the bacillus tuberculosis was not 
found. Examination not regarded as conclusive. 

Chronic Phthisis. — J. B., a man aged 40 years ; married ; 
plate printer. Decerning 28, 1897. 

Has worked in a plating factory (bronze) for 8 years. 
Onset sudden ; began to cough and expectorate muco-puru- 
lent matter November 1, 189 1. Condition has persisted for 
past 6 years; morning cough and almost daily expectora- 
tion. For past 7 months dyspnoea on exertion; evening 
temperature. Under medical care for 5 years; thinks he 
is no worse than one year ago, save increased dyspnoea. 
Has had 3 tubercular ulcers (laryngeal); 2 disappeared 
under treatment, third remains. Xo history of consump- 
tion in the family. 

Physical Examination. — Inspection : Emaciated ; waxen 
skin ; marked dyspnoea ; incessant cough ; impairment of 
motion in infraclavicular spaces ; clavicles conspicuous ; 
heart beat accelerated ; respirations more frequent than 

Palpation : Skin warm and dry ; increased vocal fremitus 
both upper lobes, especially right. 

Percussion : Marked dulness upjKT lobe, right, less 
marked on left. 

Auscultation : Increased vocal fremitus both upper lobes ; 
cavernous breathing on right ; subcrepitant rale right lower 
lobe posteriorly; friction rale on left, low down. 

Examination of Sputum: Ricillus tuberculosis found. 

Treatment : Electric arc bath ; exposure 35 minutes ; 
temperature, 90 F. 



Twenty treatments given, extending over a period of 
7J weeks. At first visit, incessant cough from time of en- 
tering clinic room up to going into hull. Just before con- 
elusion of bath marked moisture of palms, hands and fore- 
head observed. 

Sensation of bath pleasant; coughed hut once during its 
continuance, and but once for 25 minutes afterward. Two 
days later, at second visit, stated that he had coughed less 
since treatment than during the same time for 2 months 

At conclusion of second treatment hands and forehead 
moist as he to re ; \m> COUgh; freer and easier respiration dur- 
ing bath. 

At the third visit reported less dyspnoea. At the fourth 
visit. January 6, 1898, no cough night of previous treat- 
ment, January 4; once night of 5th; not at al] during day 
of 6th. Rate of respiration diminished from 40 before first 
treatment to $0, 

At the fifth visit. I 1 days after coming under care, dysp- 
noea diminished; able to walk several blocks without get- 
ting out of breath. 

Expectoration of a saltish tasti instead of sweetish as 
before, more nearly normal in color, contained less purulent 

At the sixth visit, 2 weeks from beginning of treatment, 
had an irritative cough, with discharge from posterior nares. 
Walked 10 blocks 2 days previously ; dyspnoea slight; ex- 
pectoration decreased; color of skin improved; sleeping bet- 
ter; no cough while at clinic, an hour and a half; laryngeal 
ulcer healed ; throat much less anaemic. Throat examined 
January 10 at Throat Clinic, New York Polyclinic, heal- 
ing of ulcer also noted. 

At the first 6 visits the electric arc bath alone was used, 
Beginning on the seventh, and for the remaining 14 treat- 
ments it was followed by the static electricity, positive insu- 
! nun, emivective discharge with ennui electrode, to mm 
utes, and with brush electrode, to entire general surface 


(nutritional) localized to chest walls front and back (lungs), 
5 minutes. 

During seventh bath no cough. Three and a half weeks 
after coming under care increased strength ; brighter facics ; 
better color; eyes not so preternaturally bright. Improve- 
ment continued, characterized by diminished cough, expec- 
toration, improved appetite and sleep. On January 18, 
nasal and throat examination revealed hypertrophic rhinitis 
and pharyngitis. For this 2 applications of intranasal 
cupric electrolysis were made at intervals of 9 days. About 
the first of February for a day or two appetite not good; 
cough slightly increased. Sputum examined on admission 
to clinic 2 weeks later, and again at end of 4 weeks ; bacillus 
tuberculosis found in every instance; fewer in the field at 
last examination. 

At no time while under treatment did patient have special 
nursing, and exceptionally sufficiently nourishing food. 
This was especially true during the month of February. 
February 22 admission was obtained to St. Luke's Hospital 
in order that he might have care and nutritious food during 
the trying weather of the spring months. For the first 1 1 
days gained 5 pounds, which he lost in the next 10 days. 
Three weeks after entering hospital complained of sore 
throat. Examination revealed 2 tubercular ulcers on laryn- 
geal cartilages. In the hospital until April t ; unable to 
swallow food; discharged April t, 1898. Returned to clinic 
April 7, 1898. Emaciated; extreme pallor; dyspnoea, and 
exhaustion. Xo physical examination made because of the 
patient's great exhaustion, but the following treatment was 
given: Static electricity, positive insulation, convective dis- 
charge, chain in hands, with crown electrode 15 minutes, and 
with brush electrode to the entire general surface (nutri- 
tional), localized to the chest walls, front and back (lungs), 
and over laryngeal region (ulcers), 10 minutes. 

Patient felt brighter and stronger after treatment, dysp- 
noea lessened, improved circulation, return of color to face, 
able to get downstairs more comfortably. The query 



naturally rises, might not the improvement established 
have maintained itself if the j>atient could have had con- 
tinued treatment while in the hospital, where food and care 
were provided? It is impossible to answer the question 
now, but it seems reasonable to believe that under proper 
conditions the continuance of the treatment would have led 
to better and more permanent results. This patient was liv- 
ing a month since (about August 7) and up and about. 
( Muring to change of residence cannot ascertain his condition 
at this writing. For several years he had been given creo- 
sote, nor was it discontinued when he came under care, on ac- 
count of his desperate condition. The relief obtained, how- 
ever, was coincident with the establishment of his treatment 
by means of the electric bath, and progressive tinder its use. 

Acute Phthisis. — B, B., a woman aged 35 years, single; 
seamstress. January 4, 1898. 

Patient had la grippe 5 or 6 years ago; pleurisy 4 years 
and Sine* then when she takes cold suffers pain in 
breathing, left side. In May, 1897, contracted a severe cold ; 
tired; pains all over body; knees, ankles, and hands stiff ; 
in hospital 8 days ; improved. Has not been fully well since ; 
now pain and stiffness in shouders, arms, fingers, and feet; 
badly nourished ; constipated. For malnutrition and rheu- 
matism the following treatment WES given: Static electric- 
ity, negative insulation, disruptive discharge* sparks long, 
clean and percussive to entire general surface (nutritional), 
localized to affected joints (pain and disability), and to 
lumbar and sacral plexuses, hepatic area and abdominal 
walls (constipation). Eighteen treatments were given, ex- 
tending over a period of 4 months, establishing marked nutri- 
tional gain, with great relief from pain and stiffness and 

Patient discontinued regular attendance April 2, 1898. 

( »n April io + 1K0K, returned, complaining of sore feeling 
through chest, with miico-ptirulcnt expo n. Usual 

treatment given, but could not remain for physical exami- 


May 3, 1898. — Physical examination: Congestion of 
right lower lobe, difficult breathing ; hard, dry cough, scant 

Treatment : Electric arc bath ; exposure 30 minutes ; tem- 
perature of bath, 90°F. Nine treatments given, covering 
a period of 5 weeks. Following first treatment respiration 
freer and easier; appearance brighter. May 5, sputum 
examined, bacillus tuberculosis found. At the second visit 
looked much brighter, less worn, no sense of oppression in 
breathing since last treatment, cough looser. Physical ex- 
amination made at time of fourth treatment showed sibilant 
and sonorous rales, and elicited the fact of moderate ex- 
pectoration. After fifth treatment patient felt stronger; 
coughed less. Continued improvement characterized by 
increased strength ; more energy ; diminished cough and ex- 
pectoration, freer respiration. Clinic closed June 11 for 
summer holidays, therefore further treatment could not be 
given. Arrangements were made to send patient to the 
country under the auspices of an association for the relief 
of working girls, the subjects of tubercular troubles. Over- 
fatigue and exposure to night air incident upon her going 
for the necessary physical examination by the physician of 
the association brought on an exacerbation of her trouble, 
and she did not leave the city until July 30. On August 
16 reported by letter from Franklin County, New York, 
that she had gained 3 pounds, and was much better. 

Acute Phthisis. — M. E. L., married. Came for consul- 
tation March 31, 1898. Family history good; no consump- 
tion; patient had systematically overworked in the active 
care of a large business concern; general health poor for 
several years; worse for a year past. 

In the spring of 1897 began to cough, lost strength and 
flesh. In the same summer took a sea voyage and was ab- 
sent from his business several weeks. Nutrition improved 
and cough diminished during this time, but soon after his 
return took cold, cough returned with loss of flesh and 
strength and increasing nerve irritability. In September he 


was seen by his physician and examined also by Dr. Dela- 
held. Trouble was found at the apex of the ri^ht lung, and 
bacilli in the sputum. Dr. I Vlaheld told him he must give 
up his business and go elsewhere in order that he might 
be under suitable climatic conditions. The patient was very 
much averse to this, and decided that rather than give up 
his business interests and go away he would work as long as 
he could in order that he might provide in the best possi- 
ble manner for his family and accept the inevitable when it 

He did nothing during the winter and early spring, save 
lo take COd»livef oil and hvpoplinsphitcs. At the time he 
came under care. March JI f 1898, he WM 8 good deal worn ; 
nervously irritable; had lost and was still losing flesh; 
coughed a good deal, especially in the morning and at night ; 
wakened by cough l>etween 4 and 5 in the morning; 
expectoration muco-puruknt ; appetite poor and 

Physical Examination. — Inspection : Patient fairly well 
nourished. Clavicles and ribs somewhat conspicuous. 

Palpation : No change in tactile fremitus. 

Percussion : Slight dulness over upper lobe on right, 
front, and back. Note normal on left, front and back. 

Auscultation: Subcrepitant rales above and below clavi- 
cle on right over area of upper lobe. Voice and breathing 
slightly bronchial ; increased vocal freniitiiv 

Examination of Sputum : Bacillus tuberculosis found. 

In answer to his question as to whether anything could 
be done for him, the remedial value of sunshine, whether 
natural or artificial, and the function of electricity to im- 
prove and to restore nutrition were briefly outlined, and the 
improvement of several cases of phthisis under the influence 
of the electric arc bath detailed. 

He decided to place himself under care, and treatment 
was instituted on the same day. For the first 14 days 
treatments were given daily, with the exception of the inter- 
vening Sundays. 


Treatment consisted of the electric arc bath : temperature 
of bath, 90° F.. exposure varying' from 30 minutes to an 
hour. There was an immediate diminution of the cough, 
with gradually diminishing expectoration. Improved appe- 
tite and sleep, and marked lessening of nerve irritability. At 
the end of the first week of treatment the patient had gained 
3 pounds ; cough was markedly diminished ; sleep and appe- 
tite improved. Improvement continued, and 2 weeks from 
the day he came under care physical examination was nega • 
tive, save for a slight increase of vocal resonance at the 
apex of the right lung. In an examination of the sputum 
2 weeks and 3 days from the time of instituting treatment 
no bacilli were found. The gain at that time in weight was 
5 pounds. Throughout the rest of April and during May 
almost daily treatments were given, Sundays excepted, and 
an occasional week day. In one instance only was there an 
exposure of an hour, and that at the request of the patient, 
to whom the bath was most grateful, but it was followed 
by unusually profuse perspiration with slight exhaustion. 
After that time 50 minutes was not exceeded, while the 
average time was 45 minutes. During the month of 
June and the first week of July an average of from 3 to 4 
treatments a week were given. At the beginning of the 
fourth week he was directed to secure a third specimen of 
sputum for examination, but at no time, either in the night 
or morning, was he able to secure anything, though he car- 
ried a l>ottle in his pocket for this purpose for the following 
2 weeks. There was absolutely no cough or expectoration. 
Improvement in appetite and sleep continued, with a further 
increase in weight, entire disappearance of nerve irritability, 
and withal a general sense of well-being. During the month 
of June his business necessitated his going into a new build- 
ing, which had not fully dried out, and as a result he devel- 
oped malarial symptoms. He bad at different times in 
his life suffered from chronic malaria. At that time he 
was given an anti-periodic, which was the first and only 
medicine given him while under treatment. Cod-liver oil 



was not used, but as much cream was taken as he could 
dig* - 

In all 66 treatments were given, extending over a period 
of 3 months and io days. In the second week of his 
treatment the electric arc bath was omitted for 3 or 4 days, 
owing to an accident to one of the lamps which was not 
promptly repaired. 

Following the arc-light hath the following treatment was 
administered: Static electricity, positive insulation, con- 
vective discharge with the crown electrode, 15 minutes. 
and with brush electrode to the entire general surface. At 
the same time a hypertrophic rhinitis with hypertrophy «>f 
the posterior turbinated bodies was treated with cupric 

The applications were made with a thin copper electrode 
having concavo-convex surfaces, by means of which an ac- 
curate localization of the oxyehWide of copper was made 
directly over the turbinated bodies. Before instituting nasal 
treatment there was difficulty in breathing, with profuse 
post-nasal dropping and constant hoarseness. These symp- 
toms were of several years" standing. In addition to the 
nasal treatment a slow interruption of the induced current 
regulated to the patient *s toleration was used by percuta- 
neous applications to the throat, i.e., from Bide to side for 5 
minutes, and from nape to larynx for 5 minutes, daily* As 
a result of nasal treatment nasal respiration became abso- 
lutely free, and post-nasal dropping stopped entirely, 

The throat became very much stronger under the use of 
the induced current, with gradual disappearance of the 
hoarseness, which returned but once while under care, when, 
owing to a sudden change one late afternoon from the ex- 
treme heat prevailing, he took CO]d. He came to the office the 
following morning with an acute laryngitis, exceedingly 
hoarse, with almost a whispering voice. The usual treat- 
ment was given: Electric arc bath, followed by convectiwe 
discharge, and the application of the induced current to the 


He left the office at conclusion of treatment with practi- 
cally a normal voice, and maintained his improvement. 

His total gain in weight up to the end of the first week 
in July was 8 pounds. He is a man of very slight build. He 
attended his business every day, not losing an hour, save 
the hour spent in the office for the purpose of treatment. A 
note on the 6th of July, stating his inability to keep an 
appointment, ends with the remark, "Feeling fine." On the 
9th of July, writing in reference to being away for his vaca- 
tion, he stated that he was very well. 

This patient has been given to understand that the main- 
tenance of his improvement depends very largely upon him- 
self, that every attention must be paid to all matters of 
hygiene, and that he must have outdoor exercise and sun- 
shine. Realizing fully the nature of tuberculosis, it follows 
that if at any time his nutrition falls below par the bacilli are 
apt to become active and the trouble develop anew. 

The positive results obtained in this case as well as the 
improvement obtained in cases of much longer standing are, 
to say the least, suggestive. Five years later patient re- 
mained well and continued in charge of his business. 

Acute Phthisis. — M. T., a woman, aged 28 years, single; 
importer. July 9, 1898. 

Father died of pneumonia ; mother has chronic malaria ; 
one brother died at age of 6 with "brain trouble." Patient 
not strong and always nervous as a child. Menstruated at 
age of 12, usually pain for 24 hours before flow, duration 4 
days, amount normal. Has occupied her present position for 
8 or 9 years, and has overworked ; meals irregular ; for past 
4 years much mental worry. Life indoors most of the 
time. Four years ago last February began to go to Paris 
twice a year to buy goods, since that time less strong; for 3 
years tired all the time ; unable to get rested ; very nervous 
and has lost flesh during last 2 years. Last February took 
cold, nose and throat first, finally lungs. 

Since then has had a cough, especially on retiring and 
rising; at intervals muco-purulent expectoration. Every 2 



weeks since has had an attack of coryza with incessant sneez- 
ing and nasal discharge ; malaise and great fatigue. At time 
of coming Under care* morning and evening cough, worse 
in morning, wakens her, mucous expectoration, at times 
mueo-purulent. Bowels constipated, micturition frequent. 
July 13, 1898, examination of sputum and Bacillus tubercu- 
losis found. 

Physical Examination, — Inspection: Patient poorly 
nourished; retraction of chest walls above and below clavi- 
cles, especially on right : skin inactive, pigmented in defined 
areas over sternum. 

Palpation: Vocal tactile fremitus normal. 

Percussion: Percussion note, anteriorly and posteriorly 
over upper lobe of right long is of higher pitch and of 
shorter duration than normal. Note over left dust normal, 

Auscultation: Vocal resonance increased over Upper 
lobe on right; suhcrepitant rales below right clavicle; dimin- 
ished breathing. Left side anteriorly sounds normal : pos- 
teriorly infra scapular region loud sonorous ral 

July 25. 1898.— Sputum examined and Bacillus tubercu- 
losis found 

Treatment: Electric arc hath; exposure 20 minutes to 
an hour. The shorter exposure was given on the hottest 
days. Eree perspiration always established with improved 
color and rested appearance. At the end of the first 5 days 
cough markedly diminished both night and morning, expec- 
toration decreased. For the first 8 days treatment given 
daily except on Sunday; during the 2 weeks following treat- 
ment was administered daily with one exception, while the 
last week but 3 tre a t me nts were given. 

August 5, 1898. Physical examination: Skin of better 
Color, less dry and harsh ; respiration freer ; volume in- 

Suhcrepitant rales: no sibilant or sonorous rales. Per- 
cussion note improved. Sputum examined and Bacillus 
tuberculosis found. 

At intervals of 5 days 3 applications of cupric electrolysis 


made to hypertrophied turbinated body, inferior left, 5 
milliamperes, 3 minutes each. At the end of 2 weeks, in 
spite of the heat of the summer weather and continued appli- 
cation to business, there was a gain of one pound : improved 
appetite and sleep ; general sense of well-being ; no cough at 
night, rarely in the morning; scarcely any expectoration, 
save from the throat. Menstruation established August 1, 
free from pain, very comfortable. Is to sail for Europe to- 
morrow, August 6, to be gone 5 weeks. This patient re- 
mained well when last heard of some 5 years after coming 
under care and able to attend to her business. 

Case VI. — J. G., male, aged 20 years; shipping clerk. 
August 19, T898. Father dead ; mother living and well ; one 
sister, one brother, both well. For the last 2 or 3 years not 
well, chronic malaria. Began to run down in April last, and 
had a severe haemorrhage, pulmonary, at that time. Went 
to the country, absent until July 4. No haemorrhage dur- 
ing absence. Made some gain. Since return has steadily 
lost flesh, troublesome cough, with expectoration : sense of 
malaise; poor appetite. Tn July had a very severe haem- 
orrhage, lost a good deal of blood from which he has not 
recovered. On July 31 consulted Dr. C. O. Maisch, in- 
structor in diseases of children, New York Post-graduate 
Medical School and Hospital, who reports the following: 

"Slight dulness over left apex, anterior more marked ; 
accentuated breathing. Vocal fremitus slightly increased, 
no rales. Right lung over apex a few sibilant rales, respira- 
tion over both lungs very much restricted. Retraction of 
intercostales and some dyspnoea always present. Expectora- 
tion moderate, cough not very troublesome. Haemoptysis ; 
anorexia; malaise weakness; emaciation progressive. Spu- 
tum contains a very few tubercle bacilli. Temperature, 
1 00.2 ° ; pulse, no. 

"August 12. — Physical examination: Over left apex 
dulness to within an inch of inferior angle of scapula, and 
over this area there is marked increase of vocal fremitus; 
bronchial and tubercular breathing ; crepitant and subscrepi- 



taut rales; moist mucous rales ever the entire surfao. 
dicated. Right lung unaffected. General condition much 
se, Temperature, 101.5 ! pidsCj '-20; cough trouble- 
some and expectoration considerable, 

"August 20. — Patient in same condition; complains a 
great deal of weakness/' 

This patient was referred to the writer for treatment 
August [i Physical examination was not made nor 

treatment instituted until August 20. At that time patient 
presented appearance of a very ill person, loss of flesh, great 
difficulty in breathing, rise of temperature, evening and 
morning cough most marked, occasionally during day, 
moderate expectoration, poor appetite, regular bowels, 
malaise, great weakness, and walked with difficulty, even a 
few steps. 

Physical Examination. — Inspection: Patient much a 
dated, ansemic; chest walls retracted; left chest flattened, 
with impaired motion. 

Palpation : Marked increase of vocal tactile fremitus over 
left chest anteriorly. 

Percussion: Marked dnluess over upper half left lung 
anteriorly and posteriorly. 

Auscultation: Crepitant and snberepitant rales over area 
of dulness on left; vocal fremitus markedly increased; 
harsh breathing. Right side normal. 

Patient very weak and obliged to sit several times dur- 
ing the examination. 

Treatment: Electric arc bath; exposure 20 to 30 min- 
utes; temperature, 50°F.J followed by static electricity, 
positive insulation, convective discharge with the crown 
electrode for 15 minutes, and with brush electrode to en- 
tile general surface (nutritional) localized to chest walls 
front and back f lungs 1 for 5 minutes. Afterward sat upon 
the platform for 5 to to minutes daily with ground connec- 
tion removed and discharging rods within sparking dis- 
tance of one another. During this time directed to breathe 
deeply and steadily of the ozonized atmosphere. 


Daily treatments given up to August 27, excepting the 
intervening Sunday, and save in two instances the exposure 
lasted for half an hour. From the beginning of treatment 
there was a marked lessening of dyspnoea, increasing respi- 
ratory capacity, slight diminution in cough, with, as a rule, 
less expectoration. 

On August 25 appeared very much better; facies 
brighter; respiration freer; coughing only in the morning, 
and less than before; taking sufficient food, but without 
special appetite; lowered temperature and diminished pube 
rate; able to walk 5 or 6 blocks without much effort. On 
the 26th and 27th had rather a sharp attack of diarrhoea, 
which caused considerable weakness. From August 19 
the weather was excessively hot, with great humidity, and 
as patient's home was a single room in a tenement house in 
the most crowded portion of the city, he was unable to get 
much rest at night. 

On August 2j referred back to Dr. Maisch for ex- 
amination with the following result: Temperature, 99° F. ; 
pulse, 115; general condition of patient improved; dyspnoea 
less troublesome (very much); cough less. Lungs: Left 
apex, dulness as before, has not extended. Rhonchi seemed 
fewer in number, and would indicate that liquefaction was 
not so great as at last examination. Right lung not af- 
fected. Moderate diarrhoea. To patient, physician stated, 
"You are very much better." Treatment : August 29 as 
before. Slight diarrhoea ; coughing but little, and in morn- 
ing only; raising less than before. In answer to an in- 
quiry as to why the patient did not return for treatment, the 
following letter is quoted : 

"223-225 E. One Hundred and Seventy-sixth St., 

"New York City, September 7, 1893. 

"Dkar Dr. Clkavks: Yours of the 2d hist, in reference 

to J. (i. received. I had heard nothing of him, and so 

looked him up yesterday at his home in Uaxter Street. lie 

has been in bed some days. I found him with temperature 



E04 I ., pulse 120, and in pretty bad condition. He has an 
acute pleurisy on the left side anteriorly. The physical 
signs in the chest have not changed since I saw hii 
that he has developed a diffuse bronchitis, involving both 
sides. Mi^ general condition is worse; his surroundings 
are bad, and the hygienic conditions hopeless. He has had 
no haemorrhage. Should he get up again he will come to 
vou. Yours, 

"C O. M/' 

Summary: Of the cases reported, all save 2 were dis- 
pensary patients, for whom there could he neither change 
of environment nor dietary; 2 were incurable, and yet there 
was a modification of all the symptoms, with, in one case, 
healing of a chronic tubercular ulcer of the larynx in 2 
weeks* time and with but 5 exposures, The author has no 
thought that in light energy, whether solar or the electric 
arc, a panacea for tuberculosis is to be found — far from it; 
but the uniform results obtained in the preceding sen- 
cases, which were very carefully studied, as well as in the 
practice of others, 

In a case of pulmonary tuberculosis reported by Sciascia, 
the duration was only 2 months, and while the physical signs 
were not positive, the tuberculin test a decided re- 

action. The symptoms of the disease began to subside in 
40 days, and 20 more applications resulted in recovery. 
Seven years later the patient remained well. Sciascia is of 
the opinion that the treatment would be of value in the pre- 
tuberculous stage, but that later it can only strengthen the 
natural forces, and diminish the tendency for the dis 
to spread. In this the author concurs. 

Freudenthal, Kimc. Poveau de Courmcltes. and others 
regard light energy as of very great value in curative cases 
of tuberculosis. 

The results of Kime with concentrated solar energy I 
Chapter XI.) are corroborative of the author rienoe 

with electric arc light energy. Similar results have since been 


obtained by Doumer and Finsen, and in this country 1901- 
1902, by Hopkins. More recently M. Foveau de Courmelles 
has had the same clinical experience with pulmonary tuber- 
culosis and has also treated tubercular glands, fistula, and 
joints with good results. It is well established that short 
and high frequencies or chemically active energy are the 
curative frequencies. In most pathologies other than those 
of the skin, all the radiant energy of the arc is of value. 

Tuberculosis of the Bowels. — In a case referred to the 
author with a diagnosis of tuberculosis of the bowels, woman 
aged 32, presenting the classic clinical picture, impaired apa- 
tite and digestion, especially intestinal, attacks of diarrhoea, 
emaciation, hard rigid abdomen ; there was obtained from 
the first exposures in the electric arc bath a softening of the 
abdominal walls, with disappearance of rigidity. This was 
followed, as the treatment progressed, by improved appe- 
tite, increased digestive power, cessation of the diarrhceal 
attacks, lessened anaemia, increased weight, all pointing to 
the general nutritional gain. The patient had had pulmon- 
ary complications, and at one time bacilli in the sputum. 
The cough, expectoration and bacilli had disappeared from 
a long residence in Colorado, but the intestinal complica- 
tion had not yielded to any form of medication, diet or to 
the climatic change. This patient made a good recovery, 
although never strong nor robust, and when last heard from 
2 years after treatment remained well. The entire nude 
body was exposed to the action of the light in the electric 
arc cabinet described, for from 25 to 45 minutes at first 
daily, and then every other day. Tt was followed by the 
use of the convective discharge of static electricity with 
crown, and to the entire general surface. The patient was 
under care 2 months. 

In a historic sketch of some of the so-called cures for 
pulmonary tuberculosis, J. l£. Stubbert 1 presents a few notes 
on latter-day treatment. The various therapeutic methods 

'Medical News, April 9, 1904. 


in vogue to-day, including drugs, light, electricity, water, 
scrum, intravenous and subcutaneous injections, etc., are all 
considered. In the litfht of present knowledge, diet, hygiene 
and fresh air are universally accepted as the foundation of 
all scientific treatment Upon indication they must be sup- 
plemented by symptomatic treatment in the way of anti- 
septics, tonics and surgical interference. The probability 
Stubbert believes is that within 3 years notable advsne 
immunization, and the stimulating effect of light will be 
seen, Strebel states that the good influence of electric light 
on the strength and nutrition of the tuberculous, if not too 
much reduced and debilitated, seems, according to his expe- 
rience, incontestable. Ft is well in this connection to recall 
the experiments of Bergd upon ciliated corpuscles. Upon 
exposure of a ciliated corpuscle that had been in the dark- 
ami was inactive, to the action of light it commenced to 
oscillate again. In tubercular en- iliated corpuscles 

are inactive b he bronchi are filled with a quantity of 

ion. These corpuscles require an extraordinary stimu- 
lus in order to take on their movement again. This stimulus 
is imparted by the light energy of the arc, also by that of 
sunlight. In both instances the chemically active blue, 
indigo and violet frequencies, which are very penetrant, 
penetrate the deepest bronchioU, and exercise a direct in- 
fluence upon the ciliated epithelia. From the stimulus of 
light energy they resume their oscillatory movement, in 
Other words, they take on their function and the accretions 
are carried to the upper parts of the bronchial tract, from 
winch they can be removed by expectoration. This physical 
explanation of the action of light energy in rendering 

ration less difficult is the one made by Frcudenthak 
In this connection he states, "1 remember one patient who 
was driven to my office daily up to 2 days before her death 
in spite of high fever and other distressing Symptoms as 
she always tell so much easier after exposure to the electric 
light. She could expectorate better and had less pain and 
r, In incipient cases yon may bring about a cure 


by these means. I believe that some of my cases have been 
cured in that way, but in advanced tuberculosis electric light 
is only a palliative measure of occasionally great value." 

Freudenthal 1 reports the following cases: 

Case I. — A. R., 24 years of age, a drummer, came to 
me Sq>tember 6, 1900. He had been well up to a week 
before, when he caught a severe cold. Since that time he 
had had intense pain in the throat, more so at night ; could 
not swallow food, although he was hungry. He admitted 
he might have had a slight rheumatic attack before. The 
examination showed an acute left tonsilitis and ulceration 
in the left pharyngeal fossa, Ixrth of which were attributed 
to rheumatism. In a few days the ulcer disappeared under 
salicylate of sodium and local astringents, and so did to 
some degree the pain. But very soon he felt it again, "far- 
ther up." The left tonsil was more swollen and sonsitive to 
the touch. 

Sept. 10. — Tonsil more swollen, no abscess; (edema of 
the uvula and neighboring parts on the left side. Severe 
pain. Electric light was applied for 45 minutes to the left 
side of the throat, with the result that for the first time in 
2 weeks the patient slept well. 

Sept. 11. — Oedema has disappeared, the tonsil is much 
less swollen and much less sensitive, and he feels comfort- 

Sept. 20. — Says he does not regain his strength. Has 
some pain over the chest. On examination, some rales 
were found over the left clavicle anteriorly, bronchial 
expiration and tul>ercle bacilli in the sputum. lie was 
treated daily with electric light for about 5 weeks, when all 
the symptoms had disappeared. He went back to business, 
and has been in good health since. 

In this case the effect of the electric light application to 
the tonsil and uvula was simply remarkable, and the patient 
was most grateful. The primary conditions, however, were 

*N. Y. Mid. Journal, July 12. 1 <*>_>. 



believed to be of a rheumatic nature, although the pain was 
very great When, later on, tuberculosis developed the re- 
sult was not so quickly obtained as in the beginning, but 
when obtained was extremely gratifying. 

Case II. — Miss M., aged 17, hoarse for a year, coughed 
occasionally, had night sweats, no appetite, and often felt 
dizzy. She was very anaemic, which* showed itself especially 
in the pharynx and epiglottis, while the other parts <<f the 
larynx were rather congested and partly thickened (infil- 
trations?). The lungs showed dnlncss over both clavicles, 
more marked on the left side, slight rales anteriorly and pos- 
teriorly, and bronchial breathing over the left clavicle. 
Besides, there were hypertrophies in the nose, which were 
removed. The sputum could not be examined, as she raised 
none, but there was no doubt but that the condition was that 
of tuberculosis. She remained in this city from April 25 
to July 5, 1900, after which time she went t«> the moun- 
tains. The symptoms gradually disappeared, there were no 
rales, breathing was vesicular, there was nn rise of tempera- 
ture or night sweats when she was discharged. The larynx 
was still congested, and her appetite had improved but little. 
Subsequently she was reported well. In this case of incip- 
ient phthisis a "cure" was also effected, so far as a cure 
in such cases can be obtained, which was largely due to 
electric light. 

Since the author's first experience with light in pulmo- 
nary tuberculosis there has been noted iu all the literatn 
the subject, not only the same improvement but the same 
order of improvement in the experience of different opera- 
tors which was first noticed and recorded in the writer's 
cases; an improvement which in curable cases resulted in 
recovery ; in incurable cases, in a relief from distressing 
symptoms and increased comfort while life lasted, even to 
the end. Such a uniformity of experience as to the disap- 
pearance of symptoms and result would not obtain were the 
agent used other than potent of good, til the profound 
action of the chemical frequencies of light upon the blood, 


especially upon the red blood corpuscle, thereby increasing 
its oxygenating power, is to be found sufficient and rational 
explanation of the action of light in tuberculosis. Especially 
true is this, where the naked chest walls or the entire nude 
body is exposed to the action of chemical light from jxnver- 
ful sources of light energy. 

The blood which passes and repasses in a long exposure 
through the illumined area, absorbing the penetrating chemi- 
cal frequencies, and as absorption of light energy does not 
take place without work being done, the result is an imparta- 
tion of a stimulus or energy to the absorbing media. The 
extinction of energy in space or its absorption and conse- 
quent disappearance in matter is a deep-seated fact in nature. 
If waves of light strike a growing plant they do work ; and 
to this end are absorbed all above the green. The red medium 
of the blood, with its magnitude of function, upon which life 
depends, cannot, according to physical laws, be an exception 
to the law of light absorption ; a law which has been abun- 
dantly .proven by experimental work and clinical observation. 
The absorption of light energy by the living organism is one 
of great ini]>ort. and by it the writer tolieves is to be found 
the key to read the letters of life, just as the astro-physicist 
regards it as "the key to read the letters of the universe." 

An exhibition of electric arc light energy has not only 
yielded good results at the author's hands in tuberculosis of 
the lungs but in all diseased condition of the respiratory 
mucous membrane which have offered themselves for treat- 

Among these conditions may be mentioned chronic bron- 
chitis, bronchial asthma, convalescence from la grippe and 
broncho-pneumonia characterized by constant harassing 
cough and profound exhaustion, hay asthma and acute 
catarrhal colds. 

In the treatment of all diseases of the respiratory system, 
as well as in catarrhal conditions of the nasal passages, there 
have been secured certain definite and invariable results: 
viz., improved respiration, fuller and slower, with gradually 


increasing respiratory capacity ; diminished irritability of the 
mucous memhranc* and learned discharge, Impnnrcnicnt 

m the harassing cough has invariably been noted in mi 
the first exposure. In acute catarrhal colds u rth sneezing and 
coryxa, exposure to the light energy of the arc uniformly re- 
iu in complete control at the time of these manifestations. 
If the cttndaum be taken sufficiently e<, further 

progress is arrested, 

In hay asthma a similar result is obtained. From single 
exposures of a half an hour to an hour, the riles over the 
chest and the sneezing will disappear. 

It may be thought that the clement of suggestion enters 
here. The author thinks not, for similar results though less 
rilllaat have been obtained in cases of hay asthma from an 
il energy i i > inlra-nisal cathodal 
electrolysis with mild current, 5 to 10 w the action at 

the an- per notal 

(3) vacuum tnl»c discharges from 1 static machine 
with or former. 

Frendentfaal has also had ev with this same cJ 

f»f diet. Hi hat during the last 2 years he has 

treated 24 1 w ith haj The following statement 

embodies; bii results and opinion "Out of these 14 
experienced decided improvement in all re&\ soon 

after the treatment ced. In some cases the pro- 

fuK discharge from the nose, sneezing and asthma were 
relieved right aftet the fin light. All 1 1 . 

fourth n patienti could stay in the city and attend to their 
hfftftftft, I'Ht ol course had to oome for treatment regularly. 
St* "i these 14 were treated during 2 seasons and it seemed 
as if all had much weaker attacks the second time than in the 

previous year. The res! of the ts, io. improved but 

little or left treatment too booh to form an opinion. 
"The following will serve as an illustration: 
•'Mr. C K ;, manufacturer, came under observa- 

tion September 9, 1900. A year before h was attacked for 
the fillt time hy ha\ lever, and this year it commenced as 


early as August 6 at noon( !) He had all the symptoms of 
this disease in a very aggravated form ; sneezing, running of 
the nose and eyes, asthma, insomnia, loss of appetite, etc. 
Suprarenal extract was applied to hie nose and he was ex- 
posed to the light, when he professed to feel like a new man. 
Besides he was given hydrochloric acid to take internally, 
and in 2 days he went to business again. He was seen every 
2 or 3 days until the beginning of October, when he had no 
further trouble. 

"The good result in this case was so much the more 
remarkable as this patient had been subjected to all sorts of 
treatment. He even saw a very prominent consulting intern- 
ist in this city, who told him nothing could be done for hay 
fever patients ! The following year treatment was instituted 
on July 16, in order, if possible, to avoid a recurrence. A cer- 
tain degree of success was obtained, as the symptoms were 
much less marked. Only from the 4th to the 7th of Septem- 
ber he felt quite heavy. At other times he occasionally had 
slight sneezing and rattling in his chest, which reminded 
him that he was not as yet out of it entirely." 

This one case may suffice for a series of others which 
showed similar, although not always such distinct results. 
Freudenthal considers himself justified in declaring the elec- 
tric light treatment a very important factor in combating the 
symptoms of hay fever. Whether this is due merely or 
mostly to suggestion he does not know, but the symptoms of 
hay fever arc so unpleasant and so annoying that we must 
try any remedy at our disposal to relieve them. 

The Electric Arc in Bronchitis. — T11 a case of chronic 
bronchitis in the author's practice, male, age 40. habitual 
drinker, complicated by I 'right's disease, albumen occupying 
one-third of the tube used for testing the urine, there was 
constant and harassing cough, with pink-colored sputum. 
Despite the fact that almost a week was spent in hard drink- 
ing during a period of 2 J weeks there was secured by 
the action of the light energy complete relief from 
the harassing cough and expectoration with for a time a 


slightly improved renal condition. Some 6 months later 
be succumbed to the chronic nephritis. Prior to his coming 
tint lor care he had not only been given the classic rente 
but he had spent some months in Abbeville, \\ C, and in 
Southern California without benefit. 

The fallowing case given in detail as a clinical gntdi 
illustrative of the course of these cases under treatment. 

Subacute Bronchitis. — P. \\ ",. a girl aged 3 years, De- 
cember 3, 1896. 

At the age of 16 months patient had pneumonia, at 2 
years toiisilitis, and 8 months subsequently malaria, in- 
termittent type, Two weeks prior to admission contracted a 
severe cold, characterized by febrile disturbance, loud breath- 
ing, moaning in sleep, pain through chest and cough at 

Physical Examination. — Subcrepitant rales over chest 
anteriorly and posteriorly; crepitant rales in inferior clavicu- 
lar region left ; sibilant rales right. 

Treatment: Electric arc hath; exposure 20 minutes; 
temperature of hath, */.:• I\ 

Eight treatments given. Covering a period oi 6 weeks 
and a half. Pulse and temperature records taken before and 
after treatment showed that the pulse, markedly irregular 
before treatment! became normal in character after the first 
3 treatments. It \v:is uniformly diminished in rat* 
of better volume. Upon leaving the bath the skin was warm 
and moist and respiration fo 

At the fourth visit physical examination revealed the 
presence of large mucous rales, and the mother reported that 
the cough was looser, Vfter the fourth treatment patient 
did not cough during the night. The congestion gradually 
disappeared, appetite and sleep improved, and respiration 
became normal. Patient always fell asleep in bath. Dis- 
charged recovered, No drugs given. 

September t. 1898. — No trouble since. 

Nocturnal Enuresis. 1 — J. C, 21 years of age; suffering 

'This case was first reported in 1894. 


from anaemia and enuresis. The electric light bath was 
given for 20 minutes. The patient was placed upon a stool 
within the cabinet, with the entire body exposed to the rays 
of light, special attention being paid to localizing it over the 
lumbar and sacral plexuses. The treatment was entirely 
experimental, but with the expectation of, at least, improv- 
ing the nutrition. The patient had suffered from nocturnal 
enuresis as far back as she could remember. Menstruation 
was established at 17, and was perfectly regular. All the 
conditions were normal, save that the patient was decidedly 
anaemic, and suffered from facial acne; the pupils were al- 
ways dilated, and there was a tendency to constipation, the 
bowels often moving but once in 2 days — rarely 2 or 3 days 
consecutively. The wet nights were slightly variable; she 
would sometimes go in summer 2 or 3 nights without trouble, 
but rarely for this time in winter. In all, 16 treatments 
were given, extending over a period of 1 J months, 3 times 
weekly. Careful examinations of the urine were made at 
first, and the pulse, temperature and skin were carefully 
watched. Thirteen observations were taken of the tem- 
perature and pulse. In 1 1 instances the pulse dropped, and 
it was always of better volume after the bath. In 2 in- 
stances the pulse remained unchanged but with improved 
volume; while in every instance ( 13 times) there was a rise 
in the temperature of from .1 to .8 degree. The skin al- 
ways became moist under the application and during the last 
treatments perspiration was very profuse. There was a 
general sense of well-being expressed by the patient after 
each application. Soon after coming under treatment the 
bowels became regular, and there was no trouble during the 
time she was under care, not since then, a matter of nearly 
6 months, excepting for a few days at one time after dis- 
continuance of treatment, when very much hurried making 
preparations for leaving the city, she was slightly consti- 
pated. The urine was analyzed from time to time, and 
showed a steady increase in the aim unit of urea eliminated. 
The patient gained il pounds during the first 2 weeks. 



and since that time has gained 7 pounds more, and 
is in better health than for si-vend years. The temperature 
oi the bath varied on different days, being affected by the 
k temperature, btsf ranged from 90 bo ioo°F- The 
patient always left the office feeling much better. No drug 
of am Sort was if allowed the patient during the 

time she \sas under observation, 

Ecxema. — In the case oi a young girl, aged 13, with 
chronic eczema, several years' duration, of the fingers and 
hands, when- every finger, thumbs also were cracked and 
fissured, preventing piano practice or use of embroidery 
Rosses, every crack and fissure save one healed from a single 
half hour exposure to the energy of the arcs in the cabinet 
described, So brilliant a result as this does not indicate 
that a single treatment is sufficient. On the contrary, for 
in order to secure a complete and lasting cure, it is necessary 
that the light energy should be expended over a period of 
greater or less according to the underlying conditions. 

It is only bj the establishment of nutritive chai 
the alteration of a dyscrasia, through normal oxygenation 
■ 1 the blood and metabolism, that the eczema, the exprr 
of the one or the other, will disappear. The following case 
illustrates the action of light energy in the same da* 

There was no accurate concentration of the light in 
either case as with the mechanisms for skin work. In fact, 
both cases were treated before Finsen's therapeutic w uk 
was done. 

Eczema Cruris. — A. M„ a woman, aged 29 years, single; 
maker. February 1 8, 1896. 

Presented herself because of spot on anterior surface of 
right kg, < tee year since fell and scratched her leg below 
the knee. Spot became red. infiltrated, itched moden 
with iendencj t<i moisture, stocking adherent; later crusts 
appeared on 1 be sui Eaoe, 

Physical Examination. — A patch size of palm of band 
below patella, color dull red ; covered with crusts and exud- 
ing moisture; tissues underneath thickened and swollen. 


Treatment : Continuous current, active electrode, 6 square 
inches in area over eczematous surface negative; indifferent 
electrode right foot in normal saline solution. Temperature, 
ioo°F., 5 milliamperes, 10 minutes. 

Four applications were made, extending over a period 
of 10 days. After second treatment marked hyperaemia 
over upper part of patch ; tissues softer, with partial loss of 
crusts. After third treatment several islets of healthy skin 
visible, fewer crusts; improved circulation. Because of 
general malnutrition treatment changed from local applica- 
tion of the continuous current to general nutritional treat- 
ment as follows : Electric arc bath ; exposure 30 minutes ; 
temperature of bath, 90° F. 

Two treatments extending over a period of 16 days. 
Not able to come for further treatment because of a severe 
cold contracted from exposure going to and from her work. 
In May reported through a friend that the patch of eczema 
had entirely disappeared. No drugs given. From clinical 
experience with other cases of eczema treated solely by the 
continuous current the opinion is justified that the prompt 
and complete disappearance of the eczematous spot was due 
to the action of the electric arc. The light was focused 
directly by means of the adjustable reflector or silvered 
mirror on the spot of eczema. 

Psoriasis. — No attempt has been made to treat psoriasis 
by means of concentrated light, but such cases as have pre- 
sented themselves have been treated by means of non-con- 
centrated arc light energy, in the author's cabinet. 

The cases treated therein made prompt recoveries, and 
the belief is entertained that a general treatment is much 
more efficacious in these cases than a local treatment. Here 
again the psoriasis is but an expression of the systemic con- 

A young woman, aged 18, whose body was not only 
covered with psoriasis eruption, but who was profoundly 
anaemic, lost every patch and scale in 3 weeks' time, the 
anaemia lessened with increased haemoglobin, and the gen- 


eral condition improved from exposures varying from one- 
half to three-quarters of an hour even other day. This 
patient after a lapse of 4 years has never had a similar re- 
currence. When closely confined indoors, and anaemic she 
:u»u and then a spot or two, but at no time has die 
been covered as hefore. I he conditions of her life are 
not favorable to the best of health, and she has suffered 
from anaemia from her infancy. 

Sterne also mentions having treated in his alternating- 
current arc hoth eczema and psoriasis. The following case, 
also from the author's case book, is equally illustrative. 

Psoriasis Universalis. — H. B*, a woman* aged -?6 years, 
single; nurse. April 10, 1895. 

Referred from the New York Skin and Cancer Hospital. 

Physical Examination, — General eruption over body, 
more marked on extensor surfaces of arms and legs; red 
papules covered here and there with silvery white scales ; 
no discharge; conjunctiva and gums anaemic; depressed; 
case has proved an obstinate one, and has not yielded to 
classical treatment. 

Treatment: Electric arc bath; patient nude; exposure 
30 minutes; temperature of bath. 90°F, Four treatments 
given, extending ovef a period of 9 & Fter first bath, 

circulation improved, skin warm and moist; patient felt 
warm and comfortable and looked rested. 

At second vi^it improved appetite and sleep with general 
sense of well-being. After second treatment remarked that 
she "felt that she had been bom again/' Improvement con- 
tinued, characterized by nutritional gain and clearing u; 
the skin. Treatment suspended at end of 9 days, as patient 
had to leave the city. Subsequently heard from through an 
interne of the New York Skin and Cancer Hospital, who 
reported that she was entirely well. No drugs given. In 
this case, as well as every other reported, the patient always 
looked rested and refreshed upon leaving the bath, skin 
motsl and rosy, eyes bright. 

Nervous Diseases. — The role of light energy in the 


treatment of functional nervous disorders especially, is not 
clearly established. That there is an action other than upon 
the blood, important and far-reaching as that is. seems evi- 
dent. Under the biological action of light, this has been 
considered as fully as present experimental work, superim- 
posed upon physical fact and physiological action justifies. 
The writer is of the opinion, however, that by far the most 
important action is upon the blood, and that by the absorp- 
tion of light energy of definite frequencies, a stimulus is 
imparted the influence of which extends to every organ and 
tissue of the organism. There is undoubtedly a field of 
very great usefulness for the use of light in nervous dis- 
orders. In no class of functional nervous disorders is its 
exhibition of more avail than in neurasthenics. 

It is a matter of daily observation in the author's private 
practice that in neurasthenic patients suffering from intense 
nerve irritability, exposure of the superficies of the entire 
nude body to the radiant energy of the arc, without the in- 
tervention of screens of colored glass for from 20 minutes 
to three-quarters of an hour results in lessened nerve irri- 
tability, improved circulation, and a sense of well-being 
formulated by them as a sense of "refreshment and repose," 
which is strongly at variance with their condition before 
treatment. In this class of patients, the sense of repose 
and well-being is much more marked from the effect of 
the arc light bath than from the usual electrical treatments. 
It is by reason of its nearness of physical kinship to light 
that high frequency currents serve to favorably influence 
the same class of cases. This was markedly the case of a 
noticeably neurasthenic patient, in whom the nerve irritabil- 
ity had been accentuated by reason of an exhausting men- 
strual flow associated with over-fatigue and anxiety, and 
who also suffered from great apprehension and morbid fear 
evidenced by her voice and mien as well as vouched for by 
the patient prior to treatment. An exposure of half an hour 
resulted in a more active circulation as evidenced by pulse 
and skin coloring, from absolute pallor to one of normal 



coloring, in the most marked lessening of nerve irritability, 
the disappearance of sense of appi n and a sense of 

general well-being. The improvement established by the 
one exposure continued until the next on the following 
morning. The rationale of the action necessitates, as with 
the expenditure of am form of physical energy, or for that 
matter — chemical energy in the form of drugs, repetn 
of the treatment over considerable periods of time and at 
intervals, frequent at first but later less frequently. With 
the firm establishment of nutritive changes, they should he 
discontinued, or in some cases, a more energetic or a coarser 
stimulation, so to speak, may he necessary after the first 
few weeks, in the form of electrical treatment. The ad- 
ministration of tonics, ner\e or circulatory* must be k 
the judgment of the individual physician, and should be 
given if indicated, although many patients will n: 
without their help. Perhaps no one has given more atten- 
tion to the use of light in the treatment of neurasthenia by 
the use of the chemical frequencies of light than Dr. A 
E, Sterne, 1 who presented an interesting paper upon the 
subject to the section of nervous and mental diseases, at the 
fifty-fourth annual session of the American Medical Associa- 

For the past 6 years Sterne his used the chemical 
frequencies of light in a considerable array of condil 
neurasthenia and debility, pulmonary tuberculosis, diabetes, 
syphilis, rheumatoid affections, as well as distinct organic 
nerve conditions, also in the many localized conditions so 
often encountered in neurotic subjects, notably acute and 
sub-acute pelvic inflammations and exudates. In the 6 years 
in which he has employed light therapeutically, he states that 
he has given an aggregate of thousands of treatments in a 
large number of cases, and that while there have been faib 
ures, the method has as a rule given excellent and in some 
instances remarkable results. 

'Neurasthenia and Its Treatment l>y Actinic Rays, Journal of 
die American Medical Association, Feb, -'«► 


In the treatment of locomotor ataxia and other consti- 
tutional diseases, the results from the use of the chemical 
frequencies of light have been more satisfactory than any 
other method, and he states that he has used almost every 
method of any worth whatever. But in neurasthenia and 
other debilitated conditions, the best results have been ob- 
tained at his hands from this method. They have been 
almost uniformly excellent, very few if any failures occur- 
ring. And not only were the results individually good but 
the duration of treatment has been materially lessened, in 
some instances to fully one half. This he stated was very 
clearly evidenced from a comparison between the length of 
time patients remained at his sanitarium now and formerly. 

Foveau de Courmellcs found that in some cases facial 
neuralgias and cutaneous hyperesthesias, which in general 
yielded to blue light, were made worse by blue light, but 
that they promptly yielded to the activities of the electric 
arc. Courmelles notes, in passing, the well-known power 
of the X ray to cause sudation in similar cases; also high 
frequency currents, all of which are similar physically and 

The author has found the action of both incandescent and 
arc light of value in the treatment of severe neuralgic condi- 
tions and reported in 1894, 1 relief in a neurasthenic patient, 
who was suffering from severe neuralgia of both cervico- 
occipital and supraorbital nerve distributions. The relief 
established at a single sitting lasting for several hours. 

Dr. Julius Rosenberg 2 collates a number of cases, in re- 
viewing his experience with phototherapy. lie is of the 
opinion that in light a remedy of no mean order is to be had 
and one which in the near future will occupy a most ex- 
alted position ; the possibilities of its curative action are still 

'Report of Committee on I.ij?ht as a Diagnostic and Therapeutic 
Measure. American Electro-Therapeutic Association, 1894, Transac- 
tions Am. K. T. Association. 1X04. 

*N. V. Med. Journal and Phil. Med. Journal. April 23, 1904. 


For a source of energy he uses a 55-ampere iron car 1 
arc. He regards the high amperage necessary and the spe- 
cially prepared carbons. The tfivergenl rays are collected by 
the mirrors of the apparatus, enabling him to throw and 
eentrate the light upon a given point. Exposures are from 
55 to 75 mtouteaj a shorter application he regards as nnt qj 
lasting benefit. In a sensitive skin the expenditure 

i an energy ami one so rich chemically over so pro- 
longed periods may produce an erythema but with ordinary 
care he does not find that it either produces blisters or Other 
injuries. The treatment as a rule is not unpleasant, but in- 
deed affords relief from any pain from which the patient 
may be suffering and is therefore gratifying both to patient 
and physician, 

Rosenberg reports 20 cases as follows: Neuralgia in 
right breast 7 duration, usual classical treatment, re- 

ed under 2 applications of light, duration 55 minutes. 
Severe neuralgic pains originating in left ovary in patient 
5 months pregnant, locomotion difficult and painful, reh 
entirely by 2 light treatments. Intercostal neuralgia. 4 years 1 
duration, constant pain, varying in severity, treated by 
Rosenberg for years with but little relief, disappearance of 
pain after third treatment by tight, it* return after 2 
months, Coccodynia* from traumatism, miserable for a year, 
unusual tenderness at saen •coccygeal articulation, no ab- 
normal condition of rectum or genitals, relieved considerably 
after first treatment, free from pain after 2 treat- 


arian neuralgia, left f^r years, organ enlarged and 
tender. Local treatment, tampons, etc, without much 
Kef. Patient relieved by first treatment. Apparently 
cured after 5 exposures; ovary smaller and no longer 
sensitive. Injury 5 years since, patient fell upon buttocks, 
since pain and tenderness in lumbar region, especially 
left side, very miserable last summer, spasms of erector- 
spina?* producing temporary spinal curvature; massage 
and continuous current of no benefit, seen in consulta- 


tion by nerve specialist, who advised Paquelin cautery to be 
applied and rest in bed. Slight improvement resulted but 
patient never free from pain. Pain much worse 3 weeks 
previous to report, considerable distortion of the spine, un- 
able to turn in bed, as the slightest exertion caused extreme 
agony. Relieved by first treatment, and after 5 treatments 
the patient was free from pain and able to be about. The 
remaining 13 cases include a sciatica of several years' dura- 
tion, apparently cured after 9 applications; a neuritis, 
musculo-spinal of 4 months' duration, all remedies tried, 
morphine in £ gr. doses gave transitory relief; completely 
relieved for 8 hours from first exposure and went to sleep 
for the first time in weeks without opiates. In all 12 expos- 
ures were made, and at time of report the patient was able 
to attend to business, no longer using opiates and with the 
exception of a slight rigidity no pain or discomfort. The 
remaining cases are of much the same character and were 
relieved with the same celerity. Two cases of tic doulou- 
reux will serve to complete a very interesting clinical 
report. Mrs. , a facial neuritis of 6 years' duration, un- 
told agony, most of her teeth had been removed also her lower 
jawbone. First seen 5 weeks prior to the report, could 
barely speak, every movement of the jaw painful, sharp 
shooting pains, a typical picture of tic douloureux. The 
first treatment produced a wonderful change in her condi- 
tion, she left the office free from pain, and a treatment every 
third day had kept her comfortable. She sleeps without 
opiates and is able to receive the much needed care of a 
dentist. The case was not regarded as a cure but in a few 
weeks, even days, results had been obtained, which years of 
medication and operations had failed to secure. Mrs. S. F. 
Tic douloureux for 10 years, division of the nerve at various 
points afforded either no, or only temporary relief. Ap- 
plied for treatment by advice of family physician, in the 
greatest agony. Temporary relief from exposure to the 
light but pain returned with undiminished seventy whenever 
they were removed. Treatment discontinued after the third 

3 86 

I hiliT ENERGY. 

treatment on advice of a nerve specialist, who staled (?) 
"that the treatment if continued would cause bums and 
brain injuries.** 

In a boy of to, twitching of facial musdes since infancy. 
tlie spasms bad almost entire! after 7 exposure- 

light being directed to the occiput Neither cure iiOf im- 
provement was expected and Rosenberg states that had the 
buy been an older subject, the possibility of hypnotic sug 
tlOTJ might have been considered. 

These detailed cases of Rosenberg's are corroborative 
the writer's experience with the treatment of similar 
by the electric arc light energy for the past u years. Re- 
cently, concentrated light, deprived of all the thermal fre- 
quencies, has been used successfully ( t) to relieve extreme 
cerebral congestion, one application 10 minutes in duration 
made to cervical bord with compression, 1 2) localized pain 
and soreness as a sequence of spinal hemorrhage, followed 
by complete paraplegia ; partial recover] but incontinence of 
urine, one application 10 minutes in duration and (3) in a 
<>f severe neuralgia involving all the nerves of right 
si<k* of neck, face and occiput secondary to mastoid conges- 
tion following la grippe, one exposure 5 minutes in duration. 
The paint nl area in the case of spinal hem was 

relieved at once. The case of cerebral congestion slept all 
night after the treatment for the first time in inane v 
and returned to the office the following day with lessened 
circulator] disturbance, facial tissues normal as to circula- 
tion I bad typical belladonna face and great mental confu- 
sion), qtriel mien and consecutive thought. The improve- 
ment established has continued for 3 months. Subsequently 
several other applications of concentrated light were used, 
also the connective discharge from the influence machine. 
In the case of neuralgia, the application was made jus' 
bind the ear. An erythema developed in 20 minutes, increas- 
ing in seventy for 24 to 36 hours, the sensation being thai of 
a burn. During this reactionary stage, the suffering was in- 
creased, the sensation being that of extreme congestion and 


as though every nerve trunk and branch was held in a vise. 
With the subsidence of this stage, improvement began and 
has been continuous. The severe supraorbital, ocular, and 
aural pains have passed and do not appear under the influ- 
ence of cold, damp, and fatigue as they did, while the neck 
muscles, which were not only sore but stiff, are practically 
normal. This stiffness of the neck muscles had lasted for 
6 months prior to treatment, and at this writing, 3 months 
later has not returned nor have the evidences of the action 
of light, i.e., pigmentation disappeared. Exfoliation took 
place in about ten days. There has been some return 
of the pain on exposure to cold, damp or fatigue, but 
at no time has the pain been so severe as before, and espe- 
cially is this true of the aural pain. 

The same method has been used with great improvement 
in a case of incontinence consequent upon a spinal hemor- 
rhage and complete paraplegia. Inn weeks' time there has 
been a daily increase of control and from almost daily and 
many times a day incontinence she has been free from any 
trouble about two-thirds of the time. At this writing she 
continues to improve. 

Other than the action of the chemical light frequencies on 
the blood there must be an immediate action upon the 
peripheral nerve endings, judging from the prompt and 
speedy relief from pain. 

The biological action of light is one which yet requires 
much study and investigation that it may be known 
how it acts. The fact of the absolute dependence of the 
human species for existence upon solar energy is not only 
because of the dependence of the former upon the vegetable 
kingdom, but it presupposes as well a definite relation 
between its action and the functions of the human organ- 

The Use of Light in Diabetes. — Both the incandescent and 
arc light have been employed to advantage in the treatment 
of diabetes, but because of the greater chemical activity of 
the arc, it is the better form of light to use. 



Recent ly St rebel 1 lias reported the results obtained by 
him ill the treatment of a series of eases of diabetes by means 
of the electric arc. As per the method of \hmhinow, he 
utilized a 25-ampere arc at 60 volts; reflecting the luminous 
ra\s upon a parabolic mirror from which they were directed 
Upon the hepatic area. Under the influence of the light 
activities, the skin reddens rapidly, becoming the seat of 
local sweating, which mas become general, if the source of 
Kghl is brought nearer and if the t the 

beam of light is reflected perpendicularly to the cutaneous 
surface. A rapid diminution of sugar was noted after 
several -lays' application, and finally its complete disappear- 
ance. While the results obtained h\ St rebel are most en- 
COUraging, they are not yet numerous enough to judge of 
the comparative value of the method, 

Tib of the electric arc is I tetter adapted to the 

needs of diabetic patients than that of incandescent lamps. 
It is the chemical rather than the sndative action which is 
desired primarily. 

Tn chlorotk women there seems to he a congenital weak* 
ttess of the blood-forming and blood-propelling apparatus, 
the cause of which is to he sought for in some faulty condi- 
tion of the iiu'su hhst. In them, the heart and the Mood ves- 
sels are small and the absolute number of corpuscles may he 
diminished one-half, although die relative number may be 
retained, while in the corpuscles themselves the haemoglobin 
is diminished almost one-third. This quantity of hemo- 
globin rises after the administration of iron and other reme- 
dies and also is improved to a degree by an expenditure of 
various forms of electrical energy. But in the well-marked 
and more obstinate cases of this sort, as well as in secondarv 
anremias, the author has found an exposure of the entire nude 
body to the radiant energies of an electric arc bath of greater 
avail than the exhibition of drugs singly or in combination* 
an expenditure of electrical energy or that from water in the 

tight in Diabetes: Review Internationale tTelectrotherapie et 
radiotlKraiH' January. 1904, 


recognized hydriatic administrations. The waxen pallor, the 
breathlessness. the inadequate heart, the palpitations, the 
puffiness or oedema of tissues, the lack of strength and ina- 
bility to go up and down stairs have either disappeared or 
become modified under the influence of an electric arc Ixith, 
with great rapidity. There has been an increase of haemoglo- 
bin under the influence of the light, by reason of the stimula- 
tion imparted to the swing of the oxygen atoms. For as 
each condition of matter when its corpuscles are vibrating at 
their own characteristic rates causes different sets of waves 
varying in lengths, amplitudes and periods of oscillation 1 in 
the physical world, so in the human organism must the 
characteristic vibrations of atoms or molecules cause differ- 
ent sets of waves, varying in length, amplitudes and periods 
of oscillation and the propagation of these ultimately influ- 
ences the entire blood stratum, resulting in its enrichment 
with normal constituents. 

In all the conditions enumerated showing a departure 
from the normal characteristics of the red blood corpuscle, 
the author has found the therapeutic use of light of very 
great avail, with the exception of pernicious anaemia. The 
opportunity for treating such a case has never appeared, 
and even if it did, there is very great doubt as to whether 
any good result would ensue. Still, should the opportunity 
present itself, the effort would be made, for unquestionably 
it is the red blood corpuscle which must be acted upon in 
an attempt to secure a favorable result. Drugs do not avail. 
In the stimulus imparted by the absoqrtion of the chemical 
frequencies, it is possible that the abnormally sized, irreg- 
ularly shaped, and improperly distributed red blood cor- 
puscles might assume normal shape, volume, coloring, con- 
sistence and distribution. This, however, is conjecture, ami 
is not supported by clinical experience. 

It has been stated that the action of iron administered 
internally is much more energetic when the nude body is 

1 Larkin: Radiant Energy, p. 51. 


exposed to the action of light. The author has made no 
experiments in thi> direction, bat it set ins well worth in- 
vestigating. The mam different rates at which the oscillat- 
ing corpuscles of iron vibrate, taken in connection With the 
physical and physiologic action fit light waves tlpotl the 

human organism, afford ground enough for advancing the 
hypothesis. Iron has a great affinity fot also 

have ultra-violet frequencies. Is there a sympathetic res 
asiance <•! synchronous vibration produced between the 
nee of the one within and the other without? 
The rational hypothesis of the action of light stimulus 

philis, not only upon the superficial lesions, hut the 

mic condition* is based upon its pathology of sub-oxi- 

The function of ali far as ti is Con* 

cerned is carried on by the plasma* the plasma depends Upon 
the hemoglobin for it ve energy or oxygen, and the 

red-blood corpuscle is able to store a large reserve in the 
haemoglobin compound. 

Under physiological conditions, the plasma of the triood 
is the circulating fluid within the axis cylinders, and the 
surrounding semi-fluid media or the myelin around the 
cylinders, the white matter of the cerebrospinal 
The reaction of nerve structures to methylene blue is due to 
oxygen saturation and alkalinity of the blood. In I 
dorsaliS it may he possible that the normal oxygen - 
of the nerve structures is not maintained. The indication, 
therefore, in therapeutics is for a measure which will in- 
crease the oxygenating power of the blood in order that the 
red blood corpuscles may store up oxygen. At the same 
time the product ion of a more or less lasting hyperemia of 
the degenerating cord is indicated. 

The influence thus exerted can after all only be limited, 
,ni I depends upon i be extent to which the degenerative 
process has extended. 

Clinical evidence points to a more than palliative in- 
fluence in this condition. Just so far as the oxygenating 


power of the blood stream can be maintained, and a hyper- 
aemia of the intimate circulation of the cord secured just so 
far it is possible to combat the progress of these degenera- 
tive changes. By the action of light energy there is estab- 
lished a dilatation of the cutaneous vessels which determines 
a more active blood supply to the part. This, in turn, must 
be assumed to favorably influence nutrition, enabling the 
skin, and even deeper tissues for that matter, to perform 
their functions. 

Locomotor Ataxia. — There is a considerable clinical evi- 
dence pointing to an actual improvement in this condition, 
and to an arrest of the degenerative process by the action of 
light energy. 

The physician whose case is detailed below is known to 
the author personally. The history was one of extreme 
suffering and disability. It is very probable that the injury 
was the predisposing cause with the specific infection the 
exciting cause. In addition to his tabes he was a typical 
neurasthenic. Suffice it to say that up to the time of his using 
the electric arc light he was in a most pitiable condition. At 
this writing he is in a fair degree of health, does not suffer 
from pain, »f unctions are well performed, and after he once 
has started to walk the ataxic gait is but little apparent. 

C. C. G., physician, age 46, tabes. When riding on 
April 18. 1892, while making professional calls, his 
horse became frightened, overturning the buggy, and break- 
ing both bones of the left leg below the knee, at the same 
time severely wrenching the lumbar articulations. The re- 
covery from the fractures of the leg was prompt and un- 
eventful, but the disturbance in the back persisted. During 
convalescence he suffered constant throbbing pain at the 
site of the injury in the lumbar region, pronounced pains 
occurring alternately at different points for the entire length 
of the spine, indicated the establishment of a diseased proc- 
ess throughout the cord. The pain was always aggravated 
by physical activity, and also by mental worry and annoy- 
ance. At this time a great demand was made upon him in 



the care and attention he gave his invalid wife, who died 
June 20» 1895. The extra care, anxiety and grief incn 
his physical disability. After her death he suffered from 
insomnia, and finally developed the unmistakable symptoms 
of locomotor ataxia. In tbe late snminer or fall of 1895, 
preceding the loss of the patella reflexes i\ induced 

a diminished or lo ttion of the nerves of the third toe 

of the left foot. Beginning at this time he experienced 
severe lancinating sensations in his extremities with "girdle 
sensations" about the chest. There also appeared the usual 
Sanson disturbances "1 heat and cold, while the pains in 
the back grew more severe and were continuous. The 
usual disturbance of the intestinal function was also experi- 
enced, which was followed by ulceration of the sphincter 
ani. This was in turn followed by stubborn, uncontrollable, 
diarrhoea, with from one to 20 movements daily. The 
patient suffered from urethritis, cystitis, prostatitis and in- 
continence of urine in an form. 

In the spring and summer of 1896 the pains became 
general, being no longer limited to the lumbar region and 
lower extremities. They would be felt in one loca- 

tion for an hour, or possibly for a day or so at-a time, and 
then change to other parts of the body. 

The pain in the back continued from the date oi ins first 
injury, April 18, 1892, till about the first day of May, 1893, 
A specific history in this case is very doubtful, the only 
lesion which can be associated with the possibility of such 
a Condition occurred in the summer of 1S94. An ulcer 
formed over the phalanx of the left thumb. It was char- 
acterized with a thick, heavy, indurated base, and resist ed 
the ordinary methods of treatment, requiring from 6 to 8 
months to beak There was never any other evidence of 
specific trouble, and no secondary symptoms or tertiary 
lesions ever appeared. This sore was the only evidence of 

Inline infection. 

The treatment administered for the locomotor ataxia was 
begun in the summer of 1896, and was as fellows : iodide of 


potash was administered in quantities as large as 600 grains 
daily. Following the use of the iodide strychnia was given 
in doses as large as 1 20 grain. 3 times daily. All these 
measures accomplished nothing. The patient grew con- 
tinually worse until 1898. when he became almost helpless. 
From this time no drugs were taken, as the patient felt that 
medicinal treatment aggravated his condition. After care- 
fully trying sanitarium treatment, where various plans and 
methods of treatment were adopted, he became discouraged. 
He then began the use of suggestion in the spring of 1900. 
but during this time the syndrome remained unchanged, pain 
and other ataxic conditions j>ersisting regardless of treat- 
ment. He, however, improved remarkably in his locomo- 
tion by the methodical use of a system of exercise ( Fraen- 
kel) to re-educate his muscles. Under this he gained some 
flesh and strength. There was not, however, any improve- 
ment whatever in the progressive symptoms of the trouble, 
the cord lesion. 

About March 20, 1903. treatment was instituted by 
means of an electric arc light bath. These baths were given 
in a cabinet about 5^ feet long, 4^ feet high, and 3 feet broad, 
with an arc light suspended on either end ; the space between 
the 2 lamps being from 3 to 3 J feet. With these lamps 
there was used a special carbon of German manufacture, 1 
known commercially as the plain blue carbon. Exposures 
were made daily for from 30 to 40 minutes, during a period 
of 4 weeks. At this time he had lost a few pounds in weight. 
The exposures were administered on alternate days for 2 
weeks, and then every third or fourth day for about one 
month. During this period the improvement was remark- 
able. Following the first few exposures there was marked 
relief from the severe, lancinating pains from which he had 
up to this time suffered. Relief from the girdle sensations, 
gastric crises and digestive disturbances was experienced 
from the first, and there was also marked improvement in 

*Mfg. by C. Conradi, Germany. 



the incontinence of the urine from the first. The relief 
established has continued. At the end of 6 weeks* treat- 
ment he was enabled to rest almost an entire night without 
vesical disturbance. The diarrhoea also improved, and there 
was also a marked improvement from the first in locomo- 
tion and coordination. Reflexes are still abolished. Since 
the close of this course of treatment the attendance has been 

regular. The patient a\ treatments per 

at the present time. Mis improvement in every way i^ re- 
markable, almost, if not quite unprecedented* The doctor 1 
has treated several cases since his own recovery with similar 

Alternating-Current Electric Arc Baths, — For ar arc 
light bath where uniform and extensive diffusion of the 
light is desired to act upon every part of the superficies of 
the body, the alternating current is of especial value by 
reason of the fact that the distribution of light has two 
planes of maxima of intensity, one above and one below the 
horizontal plane, This is very clearly shown in Fig. 10, 



> v : 

Fig, |l. 

Fig, 12. 

where the luminous intensity is seen to reach a maximum 
about 50° both above and below the horizontal plane. 

The contrary is true of the luminous intensity of a con- 
tinuous-current arc. as is shown in the second illustration. 

Tor the detailed history of the case, the author is indebted to 
the patient himself. 


Very little of the luminous intensity of a continuous cur- 
rent arc is produced in the regions above the horizontal 
plane passing through the arc. The intensity rapidly dimin- 
ishes as we descend below this horizontal plane, until at an 
angle 75 below very little light is emitted. It will be re- 
called that in the arrangement of the continuous arc light 
mechanisms in the author's cabinet the greatest intensity of 
light falls upon the body of the patient as they recline upon 
the couch within the cabinet. 

From Fig. 10, it can readily be seen that from the use of 
alternating-current arc light mechanisms, when the patient 
is in a sitting position, the entire superficies of the tody will 
be brought under the influence of a very evenly distributed 
light energy; but with continuous-current arcs, a recumbent 
or semi-recumbent position exposes the body to the greatest 
intensity of the light energy. 

In this direction of the luminous intensity is to be found 
the reason for placing tubes with focal lenses, as in the Fin- 
sen apparatus, in an obliquely perpendicular position in rela- 
tion to the source of light, and also the reason for allowing 
the light energy to fall perpendicularly upon the parts to be 

More recently Dr. Albert E. Sterne 1 has reported the use 
of a somewhat complicated cabinet containing alternating- 
current arc light mechanisms. In it he has placed a device 
for the generation of ozone and a Tesla coil for the purpose 
of utilizing the high frequency discharge at the same time. 
The individual operator can arrange a similar device if he so 

Since the value of light alone as a therapeutic measure 
in a given class of cases was established by the author it has 
always been customary to follow a light hath by an adminis- 
tration of the convective discharge from a static machine or 
a high frequency current. This was not done in the begin- 
ning of the use of light, but after a sufficient clinical data 

'Journal of the American Medical Association, Feb. 20, 1904. 


had been amassed to determine the action of light energy 

The more simple and uncomplicated apparatus lends 
itself to the needs of the average practitioner and an electric 
arc bath may be arranged by the individual physician which 
need neither be elaborate nor expensive in construction. 


Incandescent Light Baths. Arrangement of Light Mechanisms, 
Methods of Use, Therapeutic Indications. Obesity, Gout and 
Rheumatism, Diabetes. Anaemia and Chlorosis, Toxaemias, 

Incandescent Light Baths. 

Incandescent Light for Therapeutic Purposes. — The 
selection of a source of light energy and its arrangement 
depend entirely upon the purpose to be attained. In practi- 
cal work the indications for the energy from these different 
sources is not always absolutely clear and well defined. 
They touch at many points just as in an expenditure of 
electrical energy or for that matter of chemical energy as 
with drugs. Rut from a knowledge of the physical proper- 
ties of incandescent light, i.e., its spectrum and from its 
physical effects and physiological action, the conditions in 
which it is useful can he very clearly established. 

Principles of Construction of Incandescent Electric 
Lamps. — The principle utilized in the construction of an in- 
candescent light is familiar to all, viz., that when a strong 
current of electricity is passed through a wire of small con- 
ductivity, i.e., high resistance, its temperature is raised to 
incandescence. If the strength of the current is increased, 
the brightness of the light increases, but in a greater ratio 
than the strength of the current. At such high tempera- 
tures, wires, even of the metals fused with the greatest diffi- 
culty, fuse readily or are disintegrated. The only substance 
which docs not fuse at the highest temperature is carbon. 
The first lamps in which carbon was used were constructed 
independently by Edison and Swan in this country. To 
Edison, however, the credit is due for finding a material from 
which high-grade carbon filaments are made. This is a 



special kind of bamboo, carbonized at high temperature in 
closed nickel moulds. By enclosing an electric light in an 
opaque calorimeter, the entire radiation is absorbed, then if 
afterward it lie surrounded In a transparent calunmeter, 
permitting the light to pas>. it will he found that the lumi- 
nous r;ii[i;iii..n is about to per cent, of the total in tlie case 
of the electric arc and hut 5 per cent, in an incandescent, 
The relation between the lighting power and the streng 
current varies in different lamps according to the strengths 
of the current. 

Amperage and l . andle -l'« :>wer.— A 16 candle-power Edi- 
son lamp requires a current of 0.6 ampere. As its resistance 
when hoi is 170 ohms die potential difference at the connec 
tion according to * 'Inn's law would he the current multiplied 
by the resistance or oj6 I 70 = 102 volts. 

Life nf Incandescent Lamps — t'nder normal conditions 
the life of an incandescent lamp is from 1000 to 2OO0 hours, 
but it depends chiefly on the strength of the current passed 
through it. The I Limp is shortened if the current is 

very strong but the illuminating power varies in greater 
ratio than the current. Bulbs which have been used ovef long 
not only lose their normal illuminating power hut require a 
greater amount of current to produce that power. There- 
fore : r should be changed in incandescent light cabinets 
the minimum length of time rather than the maximum. 

Efficiency ol Incandescent Electric Lamps. — The effi- 
ciency of an electric lamp is generally given in the number 
of watts required to produce one candle-power An incan- 
descent lamp may absorb from 3.5 to 4 watts per candle, an 
arc light is much more efficient, as it gives one candle at the 
expense of less than one watt. The incandescent lamp bulbs 
on the market to-day are many of them inferior to I 
used several years since. They are more cheaply constructed, 
of shorter life an ffieiency. They therefore require 

to be changed frequently, for in an incandescent cabinet con- 
taining 50, 75 or 100 incandescent lamp bulbs, the amount 

nrrent consumed in a busy office hour is considerable 


Incandescent Light Bath — Largely a Thermal Bath. — 
The incandescent electric light bath is very largely a thermal 
bath, as the luminous efficiency is but 5 per cent, of the total 
output, but a cabinet equipped with 50 or 100 of such lamps 
gives, after all, a very large luminous output. In this per 
cent, of luminous frequencies all are to be found from the 
violet down to the red, and as they all possess greater or less 
chemical power, there is after all a very large chemical 
efficiency to an incandescent light bath. The chemical 
activity of the long, slow and less highly refrangible fre- 
quencies is sufficient to counteract any depressing effect of 
the thermal frequencies. 

Spectra of Incandescent Light Similar to Spectra of Pe- 
troleum and Gas. — The incandescent light has a very similar 
spectrum to that of petroleum and gaslight. It is poor in 
violet and blue frequencies, and rich in yellow, red and 
green. Of the three, sun baths, electric-arc baths and in- 
candescent light bathr. \hr latter occupies the third place 
in so far as chemical light energy is concerned. Sunlight 
is richer chemically than the incandescent in the blue-violet 
frequencies, while the electric arc is much more intensely 
chemical as it is used, than even sunlight, because of the 
ultra-violet energy which it emits, and which can be used 
so near the light source. 

Chemical Efficiency of Incandescent Light Spectra In- 
creased by Increasing the Current. — The chemical efficacy 
of incandescent light as evidenced photographically is. 
therefore, very slight, but this, as well as its luminous out- 
put, may be materially increased by increasing the current. 

This is shown by Abney's table. 

Number of Grove Illuminating Power Photographic 

Elements. in Normal Candles. Krtcct. 

12 0.132 immensurahle 

14 0.26 0.35 

16 1.17 1. 01 

18 -'44 5.83 

20 3.84 12.84 

22 6.85 36.45 

24 10.38 86.60 



It is not only the luminous output or optical brightness 
that is affected by increasing the strength of the current, hut 
also the quantity of blue and violet frequencies. 

Chemical Equivalent of Incandescent Light. — Tt is c 
mated that, as a rule. 380 incandescent lamps of nor- 
mal power without reflectors have the same chemical effect 
as natural light, at a distance of one metre from the 

TIk Xernsl Lamps for Incandescent Light 1 laths. — In 
the NY-rust lamp there is to be had a light richer in chei 
frequencies than the ordinary incandescent lamp. By their 
use a light twice ,is intense is obtained of a pure wlm 
rather greenish color, and, therefore, more from the chemi- 
cal end of the spectrum- < )f ail the electric energy con- 
sumed in an incandescent light bath, hut 5 per cent, is ac- 
counted for in the luminous activities. This does not in- 
clude the red, blue and violet frequencies, which bring it up 
to 30 per cent. With the Xerust | -ampere lamp, this per- 
centage is raised even to 60 per cent. 

The Radiant Efficiency of the Xerust Lamp, — The effi- 
ciency of new Xerust glowers was found by Ingersoll, 1 who 
carefully tested them to vary from 4.35 per cent, to 470 
per cent., with a mean of 4.61 per cent. The efficiency falls 
rapidly for the first 20 hours, decreasing to 4.3 per cent., 
but varies only verv slowly after this. In making these ex- 
periments Ingersoll maintained the power constant, not the 
current, as was done by Hartnian, which accounted for his 
different figures as to decrease in the efficiency. Some very 
old lamps tested gave efficiencies of only 3.6 per cent. The 
lamps were all 1 10- volt glowers, consuming 89 watts, and 
for every watt above 8t> within narrow limits, the efficiency 
increases 0.06 per cent. t and below this, vice versa. The 
energy curve ( Wiens law) gives the efficiency as 4.17 per 
cent. These testa were made in such a manner as to cut 
off all the invisible frequencies, giving only the radiant 

*The Physical Review. Nov., 1903. 


efficiency of the lamp. In common with the incandescent 
old lamps lose their efficiency, and in baths constructed 
either with the one or the other, the lamps should be re- 
newed frequently. This not only means greater efficiency 
but less consumption of current. 

The Nernst lamp, by reason of the fact that it does not 
require a glass covering, although provided with one, offers 
a means of supplying the frequencies needed in therapeutic 
work, although not to the same extent as the arc, still greater 
than the incandescent lamp. In this lamp the source of the 
light is a rod of zirconia acted upon by the electric current. 
As there is no glass enclosing bulb, there is no loss of the 
short and high frequencies, as in the incandescent. For a 
therapeutic cabinet it is useful and fewer of them would be 
required, owing to their greater efficiency. Still another 
advantage over incandescent bulbs, is that fcr the same con- 
sumption of current the number of light waves is greater, as 
less of the current is converted into the longer heat waves. 

First Introduction of Incandescent and Radiant Heat 
Baths. — Incandescent light baths were first introduced by 
Kellogg and the radiant heat baths by Hcdley. In 1894 
Kellogg presented a paper to the American Electro-Thera- 
peutic Association, giving a very exhaustive resume of his 
work with incandescent light baths. About the same time 
Hedley, of London, called the attention of the Balneological 
Society to an apparatus which he had devised for the pur- 
pose of applying to the body direct heat rays from a luminous 

Winternitz has particularly interested himself in the 
development of this therapeutic measure. 

Hedley 's device consisted of incandescent lamps, each 
carrying 2.} amperes of current, fixed in reflectors. This 
apparatus has been in use ever since. The well-known 
Dowsing radiant heat baths are constructed upon this prin- 
ciple. The devices of both Hedley and Kellogg have fully 
stood the test of time. The fundamental principle in the 
construction of baths for this purpose is the same in every 



instance. These cabinets were subsequently introduced into 
Germany by ihe chemist Gebhard, where they are very ex- 
tensively used. 

Incandescent Light Mechanisms,— Incandescent light 
mechanisms may be arranged for either general ur 
work. In the. former instance, cabint i nstrucU 

the principle of the Kellogg cabinet, and the energy of vary- 
ing numbers of incandescent tamps from SO to 100 or more 
utilized therein, Kdlogg's first use of incandescent light 
energy was with single lamps where th ilized 

and concentrated. This method is considered in detail in 
Chapter XI II. The results obtained from their use in this 
way were so excellent that he was led not only to the group- 
ing of a few lamp mechanisms for the purpose of con 
trating the light energ] upon a part, but to the construction 
of an apparatus for the exposure of the entire nude body, 

First Incandescent tight Cabinet— His first cabinet 
consisted of a frame about 2 feet in width, which sup- 
ported a metal reflector and from 20 to 30 incande- 
tamps. The frame was attached by hinges to a support in 
such a way that it could be raised or lowered at will. The 
patient was exposed in a recumbent position upon a couch 
placed beneath it during the time of treatment. When the 
one surface of the body had been exposed for a sufficient 
length of time, the patient turned over exposing the other 
-nit <^\ the body to the light energy. Later on he had cabi- 
nets constructed at first a vertical and then a horiz 
one. These cabinets are constructed at this time of differ- 
ent Eorms and sizes according to the needs uf the individual 

Incandescent baths may be arranged either for a sitting 
or a recumbent position of the patient. The principle is the 
same in each instance. As a rule, they are arranged for the 
sitting position, although one of the Kellogg cabinets \fi 
arranged for the recumbent position. 

Horizontal Incandescent Light Bath. — In this the pa- 
tient reclines upon a glass-covered couch, while from above 


him and below him, and also on every side of him, the 
energy of about ioo 16-candle-power incandescent lamps, 
reflected and multiplied by polished mirrors, is directed to 
the body superficies. The couch is movable, mounted on 
'wheels, that it may easily be run in and out. The glass cover- 
ing of the couch permits the action of the light energy upon 
every square inch of the exposed body. Here there are no 
limiting ultra-violet frequencies to prevent the use of the 
glass. The head remains outside of the enclosing cabinet 
during treatment while a curtain shields the patient's eyes 
from the action of the light. 

The vertical cabinet described by Kellogg, required to 
energize it from 20 to 40 16-candle-power lamps. Different 
operators vary the number according to the conditions to be 

These incandescent light cabinets generally, however, 
consist of octagonal boxes arranged for connection with the 
street electric wires. They may be operated either by a 
continuous or an alternating E. M. F., and the one is as 
good as the other for the purpose. They are variously sup- 
plied with mirrors, opalescent and colored glass plates, to 
be used at will. A door permits the ingress and egress of 
the patient, who in the enclosing cabinet sits upon a stool. 
There is also a movable divided lid fitted on the top with a 
hole the size of the patient's neck, and from which the pa- 
tient's head emerges. The cabinet shown in the illustration 
is one of the most complete cabinets constructed by the 
manufacturers for the purpose of an incandescent light bath. 
As will be seen it is a cabinet in which the patient sits with 
the head out while exposed to the action of the light energy. 
The framework is constructed exclusively of steel. This 
completely obviates any danger from fire in the event of a 
defective bit of insulation. It is provided with 38 lamps, 
and consists of 6 drawn sheet steel panels, steel top with 
head and hand holes, steel bottom, metal chair, with door 
at front and 2 doors in the top, as shown in cut (Figs. 1, 2 
and 3). 



Thirty spherical incandescent lamps are arranged in 6 
channels | Figs. 4 and 5 >, said channels being provided with 
Violet or rule urns, which are hinged to one side of 

said channel, and so arranged that they may instantly 
be changed or ripened to giv< to the lamps within. 

Eight lamps are also arranged around the bottom of the 
chair. Each set of lamps is on an independent circuit, and 
each may be controlled separately by means of swit 

veniently arranged on the underside of tin; top of the cabi- 
net In this manner ihe temperature within the cabinet may 
be closely regulated. 

All wiring is of the latest approvi 1 in 

steel tubes, and such as approved by the Xew York Board 
of Fire Underwriters. The wiring is so arranged tint the 
cabinet may be operated on 52 or 104- volt alternating 
current, or 1 10 or 220- volt direct current. To this end 
it is merel\ necessary to insert lamps of the equivalent 

The simplicity of the construction of this cabinet is such 
that it can be set up in a few moments by any one following 
tin- dire jtioDS, 

The channels carrying the lamps are supported on hooks 
at their back, and the lamps therein connect to junction 
boxes <>n the underside <^ the top of the cabinet by means 
of plug switches. The panels are held in place by small 
clamps, which al- ail B Bttpport for said lamp chan- 


To facilitate shipment and simplify the installation of the 

cabinet h\ a novice, it is so constructed that it may be en- 
tirely taken apart without interfeuug with any of the elec- 
trical connections or other parts. 

This is accomplished by removing the plug switches at 
the top of the channels, lifting the top off, raising the chan- 
nels from their hook supports, removing the screws in the 
clamps hul ding panels together, ami withdrawing the two 
hinge pins, in setting it up the reverse of the above direc- 
tion must be followed. 


Dr. Italo Tonta 1 made several improvements in his in- 
candescent light bath, which are worthy of attention. First 
he provided the top of the octagonal-shaped cabinet with a 
cupola-like cover, with angles so disposed that it is possible 
to concentrate the light energy uj>on the body of the patient. 
In one of the posterior faces of the cupola he has provided 
a ventilating device operated by a small electric motor, the 
speed of which is controlled by suitable resistance, as he 
regards the want of ventilation in an ordinary cabinet a 
great fault. In the thickness of the 2 lateral doors below 
are 2 openings the size of the palm of the hand closed by 
small metallic plates which are provided with mirror sur- 
face upon the inside. Those are for the entrance of dry air. 
which can be introduced into the cabinet when the venti- 
lator is in action. When these are closed and communica- 
tion established between the ventilator and the external air 
the hot air inside the cabinet is agitated. Seven circuits 
of a series of 8 lamps each are provided. These arc placed 
horizontally. The last circuit comprises 2 lamps placed 
under the bench designed for the feet. Screens of dif- 
ferent colors are provided to eliminate at will different fre- 
quencies of the spectrum. The roof of the apparatus is 
provided with a groove in which the cover, divided into two 
parts, glides. This is so arranged as to fit exactly about 
the neck of the patient. In this cabinet the refraction of 
the light is horizontal and diagonal. The walls of the cabi- 
net are of wood, covered upon the inside with mirrors. In 
the fixed part of the cover a thermometer is placed in a 
neutral zone. i.e.. a part that is not exposed to the direct 
radiation of the light. There are provided openings in the 
walls of the cabinet for the purpose oi observing the cardiac 
movements, and at the same time of the condition of the 
skin as to transpiration and by an introduction of a hygro- 
meter to estimate the humidity o\ the air. These can l>e 
opened or shut at will. An adjustable chair within the 

'The Light Bath Congress of F.lectmlogy at Herlin, Revue Inter- 
nationale d'lilcctrntherapie. Nov. and Dec., lyoj. 



cabinet permits the patient to be placed at the desired height 

This detailed description is given ; has 

many good points. The individual operator can bavt 

these details of construction embodied In his incandescent 
tight cabinet if he wishes 

The method of Ventilation the author regards as ex- 
tremely advantageotu 

tnbined Incandescent and Arc Light Cabinets. — Some- 
times these cabinets are constructed in such a manner as to 
contain both incandescent and arc lamps to be used simul- 
taneously or separately, as the operator desires. While 
combination ineamU -.- I electrical arc baths are not 

recommended they can be used where floor Space prohibits 
the placing of two equipments. They should be so constructed 
that either the light energy of the incandescent or that of 
the arc can tie used separately * n* conjointly, as desired. 
The action of the incandescent bath, as compared with that 
of the electric arc. is to lie regarded as that of thermal energy, 
while with the electric arc bath the action is primarily a 
chemical one. 

The author prefers to project the light from an arc tight 
mechanism provided with suitable reflecting mirror, as the 
marine searchlight, upon the patient seated within or with- 
out the cabinet, according tea the environment rather than to 
have electric arcs permanently placed in an incandescent 

Effects of Incandescent Light Baths and Electric Arc 
Baths not to be Confounded* — The effects of these should 
not be confounded with the effects of electric-arc baths. 
The latter whether used in such a way as to secure the 
influence of all the activities of the arc. or the exclusion of 
the thermal frequencies, is in the highest sense a chemical 
light bath because of the exceeding richness of the electric 
arc in the chemical frequencies. The latter is richer in the 
ultra-violet than the sunlight as we use it, while the former 
is not even comparable chemically with sunlight. But even 

the incandescenl baths occupy a verj important place 


in therapeutics. They are useful by means of their radiant 
heat, in addition they have a chemical power by reason of 
the blue, indigo and violet frequencies, for which the glass 
is transparent. As a source of light the incandescent lamp 
is not rich in these frequencies, but as the glass does not 
preclude the passage of those emitted, and as many of them 
are used in a given light bath equipment, from 25 to 100 or 
more, it follows that after all an incandescent light bath has 
a very decided chemical power. It is more than a sudatory 
or transpiration bath, and even so, as such, the heat produced 
is of a different quality from that which proceeds from hot 
air or steam. A number of these gathered together in a 
small area, as in a therapeutic cabinet offer very great chemi- 
cal power. Even a candle as a source of light has sufficient 
chemical power to render it necessary to use a dark red 
glass in the examination of a sensitized photographic plate. 
Advantages of Incandescent Sudatory Baths over Hot- 
Air or Vapor Baths. — The advantage of these baths as 
sudatory or transpiration baths is to be found in the fact 
that heat reaches the interior of the body by conduction, 
after penetrating slowly through the layers of the tissues 
that oppose by their inherent construction, a great resistance 
to the passage of heat rays, hut allow light waves to pass 
readily. With an incandescent light bath, even though 
applied as a sudatory bath, in conditions where profound 
elimination through the skin is desired, in Rright's disease, 
for example, the time of application is much shorter than 
with the hot air or the vapor hath. This is due to the fact 
that in addition to the thermal activities there is an influence 
also of the longer and slower frequencies; the red, yellow 
and green, as well as from the more refrangible blue-violet 
up to the ultra-violet. There is a very small per cent, of 
blue-violet emitted by a single incandescent unit of light. 
however. The red and low frequency waves are transformed 
into heat, while the higher visible chemical frequencies exer- 
cise ( 1 ) their characteristic action upon the skin and superfi- 
cial circulation and (2) upon metabolism. 


An incandescent light bath, then, ts actii n pi 

its thermal, luminous and visible chemical frequencies. The 
latter are much less than in the sun or electric arc, therefore 
where the maximum chemical effect is desired in a general 
bath, cither the sun or the arc should be selected. 

Penetration, Absorption and Transmission of the Vary- 
ing 1 Frequencies of Light Energy by the Living ! 
Kellogg found "upon examining by means of the splanchno- 

a tinman body on wh^se abdomen a single incati 
cent (amp of 10 to 32 candle-power was burning, the whole 
true pelvis shown with a bright red light." As noted on a 
subsequent page, a miniature incandescent lamp within the 
vagina will cause the pelvic tissues to within 2 inches of the 
umbilicus to glow with red light. The area of the stomach is 
beautifully outlined by the translucent] ol the tissues to the 
light of the miniature lamp placed therein for diagnostic 
purposes. It is only necessary to hold a hand before 
source of light or sunlight, for that matter, to be assuri 
the penetrability of the other rays of light, even through the 
i and to the innermost parts of the body. The 
blood absorbs the chemical frequencies of light, blue, 
violet and under pressure the ultra-violet as well, according 
to the law of color absorption. The fact of the tin 
cence of the blood indicates a penetration of the fre- 
quencies or energy of radiation which the oxygen molecule 
is capable of absorbing according to the Ibm governing 
absorption of light. The action upon the peripheral bl 
supply does not end at the periphery, but must, by its very 
nature, go mi and to the innermost depths, the degree and 
constancy of effect depending upon the character, length and 
frequency of exposure 'lit energies. It seems to the 

author that there can be no question but tint the red rays 
which penetrate so deeply and which exist in such abundance 

in an incandescent bath are of value, Just what their func- 
tion may be is perhaps not so clear as with the chemical 
frequencies, but function in the very course of nature they 
must have. 


It must not be under st-»i :ha: red frequencies are >ynon- 
omous with thermal freqix-ncies. The thermal activities 
must be regarded as invisible hea: :n c ntr-i listinction to 
such visible heat as characterize? :he re-: freq::encies. 

The Influence of Incandescent Light Energy up n the 
Skin. — There is produced by the action of these baths an 
iii tense reddening, i.e.. hyt*:nem:a of the skin. This indi- 
cates a dilatation of the superficial b]r»od vessels. This is a 
simple hyperemia, unlike that produced by the chemically 
active energy of solar light and the electric arc : and unless 
there has been an intense heat effect, scorching of the skin, it 
disappears very quick -v. a- ':■• a!: hyperemias br«»ught about 
by radiant heat, leaving no traces ■ f erythema -t of pig- 
mentation. The so renin;: effect ;.''::ded to should never be 
permitted. Kellogg fund iV-m fr-_-q::ent repetition of these 
baths that the skin did Wome pigmental or br. »wnish in 
color, as from exposure to tiv- -un'* ray*. Jt is quite possible 
that frequent repetition, prolonged application and great 
light intensity may produce pigmentation. for under those 
conditions there i- after all a considerable chemical light 
intensity operative. 

The Influence **i Incandescent Light Knergy upon Suda- 
tion. — This is one of the mo-t marked phenomena from this 
mode of treatment, and to the profound action upon the 
sweat glands much of th'* gor-d derived from its use must be 
attributed. It i* produced more quickly than by any other 
known procedure and generally appears within fn»m 3 to 5 
minutes after entering the bath and quite regardless of the 
temperature of the bath. Winternitz observed it at Sh I : .. 
30 ■■(.". Much longer time i* required in the hot air or Turkish 
bath. This action i< unquestionably due to 1 it a stimulation 
of the peripheral nerve ending* and (2) to raiding the tem- 
perature of the p-itientV b'»d\ bv the action **i the radhnt 
heat. As a chemical light bath (the electric arc. where the 
temperature of the cabinet is but little elevated > stimulates 
the activity uf the sweat glands, the inference is drawn tint 
the action is due in part to a stimulation of the jvripheral 



nerve endings which follows upon the action of the chemi- 
calk active energy of an incan light 1>atli. Vigorous 

pe r s pirati on may he induced in a small area of the body hy 
the action uf the incandescent light energy, indicating that 
the effect is due rather in the radiant energy of these light 
sources, than to the hot air uf the enclosing caYnneL The 
part d most directly to the light are first affected. 

It was observed by Kellogg that the amount of sweat 
excreted in the incandescent hath was twice as much for the 
same time as in the Turkish hath, while the average tempera- 
ture in the former was 8i c F. and in the latter was 14 
14s F. lie also noted that with 50 lamps in operation, the 
perspiration began in 6 to 10 minutes at a temperature of 
95 T\ If the temperature of the cahinet is raised to [40 to 
158 1 sweat to tin amount of a litre may he excreted in a 
quarter to a halt an hour. 

Kattenhracker found 0.26 per cent, of sulphur in the 
sweat of a glass blower, while the very interesting fact is 
noted by Bdow mm] Aufrecht that traces of mercury were 
foitttd in the perspiration of persons who had been treated 
by mercurial inunctions years before. 1 

Crothers" notes the marked action upon the secretory 
centres and that the elimination of fluid is rapid and intense. 
He finds that patients su tiering from toxaemia are 
Ebtmdly affected by the action of die light baths. In neurotic 
patients on the other hand the stimulation may not lie 
noticed for some time. This would indicate a diminished 
power "f response of peripheral nerve endings in the latter 

I fader the influence of electric light a higher temperature 
from stove heat can he borne with impunity by plants than 
without it. This was proven by Siemens in his experiments 
upon plants. 

It is the consensus of opinion that the temperature of 

'Quoted by Freund, 

Yi rk Hid Phils. Medical Journal, July 23, 1904. 
Radiant Keat Baths, 



an incandescent bath and its accompanying effect upon the 
sweat glands is better borne than a hot air bath. It is much 
more life-giving, less depressing in its action, an effect 
which can only be accounted for by the presence of the 
higher and shorter frequencies. It is not necessary in an 
incandescent bath to have as high a temperature for the 
production of transpiration as in hot air or vapor bath be- 
cause of the action of the other frequencies upon the skin. 
This action is produced by all the frequencies, including the 
red, as they all possess more or less chemical power. There- 
fore, transpirations occur at comparatively low external 

The Influence of Incandescent Light Energy upon the 
Heart, Pulse and Tonicity of the Arteries and Blood-Count. 
The statement is constantly made that incandescent light 
baths do not influence the heart's action. Experimental ob- 
servation contradicts this statement. In general it may be 
said that it does not affect it unfavorably as does hot air and 
vapor baths. M. Roth 1 observed that a pulse which before 
the light bath had lx?cn steady at 72 beats increased rapidly 
after 10 minutes in the cabinet to 84 beats. After 15 minutes, 
it gave 104 beats and after 20 minutes 132 beats. At first 
it remained fairly steady and later on it grew galloping and 
irregular. The same effect was observed by Stasser 2 and 
Strebel. 3 

Kellogg found that under its influence the pulse is first 
quickened and then slowed. Fretind observes that it must be 
conceded that with a temperature in the light cabinet at 
I22°F. the pulse is quicker each minute by about 15 to 20 
beats. Oothers 4 notes that the tension of the arteries inva- 
riably fell from the action of these baths. Contrasting it 
with the hot air bath, he found that the tension did not 
always change from the action of the latter, unless the time 

'Med. Wochcnschr., 1899, No. 19. 
*Encyclop. Jahrb. iqoo. 
"Quoted bv Frciind. 

4 Radiant Heat Bath, N. Y. Med. and Phila. Med. Journ., July 
-\3, 1904 



.it using it was prolonged. The changes in the pulse he 
found niiirc marked in the hot air than in the radiant 

usuallj rising while in the former ami falling in the 
latter. In measurements of the pulse, temperature and 
tonicity of the arteries the radiant beat hath showed great 


There is then no question of their influence upon the 
heart pulse and arterial tone, and while the pul vated 

by the profound and prima?) action upon the peripheral i ir- 
culation, still the acceleration of the heart's action is within 
limits of safety. This is m> true that with the precautionary 
measures insisted upon these baths may be used safely even 
in grave cardiac disorders. The changes which take place in 
the pulse are as a rule rial so marked in succeeding haths. 
fn< of the immediate results of the use of these baths is an 
increased blood pressure. In most caso. however, this sub- 
sides pious perspiration from a si tj of from 20 • 
minutes in the bath. Sometimes congestion, with bleeding 
at the nose, has been observed as a result of this incre 
blood pressure. This is nol general. Kellogg found the 
blood count of the red cells especially marked!) increased, 
10 b> 20 per cent., by the incandescent light hath when fol- 
lowed b) the usual cold hath. The increase appears within 
half an h*n\r. 

The Influence of Incandescent Light Energy upon t 

espiration is very markedly a fleeted by the 
baths, Kellogg notes thai it is free and unembarra 
although somewhat quickened. It becomes twice as rapid 
after a shotl Stay, 15 minutes, in the light cabinet and is at 

same time mofl shall w and superficial. 
Following these haths the respiration becomes uniformly 
regular and n< rmal. Kellogg 1 noted a decided increase in 
the elimination of carbon dioxid, evidencing the active 

n and 1 issue changes set up by their action. In his oh- 
Ltions of 1894 he noted that the average percentage of 
carbon dioxid eliminated during a 30-minute incandescent 
Ti Therapcul 1 •inn 


light bath was 5.13 per cent, in a patient who previous to 
the bath was eliminating 3.60 per cent, an increase of 44 
per cent. From a 5-minute exposure the increase was 4.10 
per cent, and for a 20-minute exposure 4.20 per cent. In a 
Russian bath the same subject eliminated an average of 3.96 
per cent., an increase of 10 per cent., while in a Turkish hath 
of 30 minutes' duration the average elimination was 4.1 1 per 
cent., an increase of 1 1 per cent. 

Action upon the Urinary Secretion. — In this connection 
it may be noted that Roth and Kellogg both studied the 
action upon the urinary secretion. The latter found a diminu- 
tion in the amount of urea, of the total chlorids and total 
solids. From Roth's nvestigation upon the urine and per- 
spiration, these baths do not seem to have any especial 
marked influence on organic decay in the body. 

The Influence of Incandescent Energy upon Body Tem- 
perature. — It was observed by Kellogg that there was quite 
a rapid rise in body temperature from the action of incan- 
descent light baths. In from 10 to 15 minutes he noted 
an elevation of from 4 to 5 above the normal. Freund 
places it about 2°F. This is noted by all observers, and 
the increase in body temperature tends to increase the com- 
bustion of fat. The increase of temperature necessarily 
varies with the duration and intensity of the bath. The 
difference between the estimates of Kellogg and Freund 
can be accounted for no doubt by the method of taking the 
temperature. In Kellogg's observation the extreme rise was 
noted upon taking the external temperature, the difference 
in the internal temperature being after 5 i -minute exposure 
1.6° F. very near that given by Freund. 

The Influence of Incandescent Light Energy upon 
Bodily Weight. — There is a marked influence of these baths 
upon body weight, the diminution bearing a relation to the 
duration and intensity of the bath and its effect upon the 

This is apt to be counteracted by too free drinking of 
water. As a result of the profound elimination through 


the sweat glands there is usually intense thirst In most 
conditions it is better tC drink freely under these conditions, 
and sometimes during the bath. In cases of obesity it is 
ssar) tn control the amount of fluid ingested, because 
it defeats the object to be attained. This should only be 
done within physiological limits, however, 

The Influence of Incandescent Light Energy upon Bac- 
teria. — This form of light energy cannot be regarded as 
bactericidal, as the bactericidal rays are placed in the mid- 
dle third of the ultra-violet region. The action of light 
energy in bacterial diseases does not depend upon an actual 
destruction of the micro-organism Ian impossibility in liv- 
ing tissue no matter what the source of light energy), but 
upon its action in producing a hyperemia of the part treated. 
There is secured by the stimulus imparted increased 
genatioii of the blood, and nutritive changes are established 
which increase the physiologic resistance. 

A favorable action of light has been noted by various 
observers on infected animals, ami in this connection Kon- 
dratiew, DeRetlZl, Kutschuk, and Aufrceht 1 may be men- 
tioned- There is, however, no specific action on the part of 

the energy of incandescent light. This has been fully < 
lished b> the mass of evidence as to the action of light energy 
upon bacteria. 

It rved by Drigalsky* that mice inoculated with 

splenic fever or other bacteria died more quickly in the in- 
candescent light bath than control animals even though they 
were kept only a short time in the bath. {Its explanation 
of this untoward effect is the rational one* viz., that the 
resisting power of these animals was reduced by the copious 
perspiration induced by the thermally active energy. 

In this connection he wisely calls attention to the dan- 
ger to mam feeble patients, such as the tuberculous, from 
its use. The author regards the use of the incandescent 
light bath as absolutely contra-indicated, and never under 

'Quoted by Boeder. 
Quj Red l>> Freund. 


any circumstances uses or recrcr.—er.fs its use in this class 
of cases. As shiwn :r. cmstierir.g the electric arc bath. 
the indication in these cases :s for the intense cheuucally 
active light energy oi the sun and the electric arc. 

As the bactericidal energy :s the sarr.e which excites 
tissue reaction it follows that incandescent light energy, 
useful as it is in a very considerable range of disease, is 
practically of but little value in the treatment oi any con- 
dition requiring intense chemical activity, as in lupus. It 
best meets on the other hand all conditions where, in addi- 
tion to a slight chemical effect, there is desired the longer 
and slower frequencies of the lower end oi the spectrum, 
active thermally. There is. therefore, no question oi using 
it in chronic skin lesions where the short and high fre- 
quencies of the blue violet and ultra-violet are so useful. 
It has a field of usefulness, however, in more recent patho- 
logical skin conditions, and especially where thermal energy 
is indicated as well. It is also of value in minor surgical 
conditions, as shown in Chapter XIV. 

Sensitization. — There is a possibility that by rendering 
the tissues sensitive by >uitable media, that the energy of 
incandescent light can be rendered more effectual. For this 
purpose solar energy or that of the electric arc are to be 

The Mode of Action of Incandescent Light Energy. — 
The physiologic effects of incandescent light baths are due 
( 1 ) to radiant heat, ( 2 ) to chemical energy. This chemical 
energy, so far as the blue- violet is concerned, is small, ultra- 
violet none, but it must be remembered that the different 
frequencies of the spectrum are thermal, luminous or chemi- 
cal in relation to the substances or structures upon which 
they fall. It is not known that the longer and slower fre- 
quencies below the blue have a chemical action in relation 
to living tissues, nor again is it known that they have no 
such action. It is known that they penetrate, and that then* 
is absorption above the red. Absorption does not take 
place without work being done. The exact nature of that 



is conjectural, ( >n the other hand, in an incudes 
bath the Mue-vioJet are to be reckoned with, their chemical 
Intensity for a single unit of light is small but far §0 to 
I GO such units it is cbnsiderablj magnified. Therefore the 
physi Ed be ascribed to a chemical as well 

as a thermal energy. The interposition of the body tissues 
suffio >rm this twofold etterg) into thermal and 

chemical energy. The skin is a poor conductor of heat, hut 
transmits radiant energy readily. The heal enters the 
as a radiant force, ami in tins way the heat is carried to the 
tissues. It is not confined to the si the case with 

conducted heat from water vapor <>r Russian or Turkish 

Moeller showed that in radiant energ\ haths the heat 
rays readily penetrate even bones. The penetrating li^ht 
rays below the blue, Le., the red, yellow and gn 
d in relation to molecular activity would seem, b] 
of their length frequency and amplitude of oscillation, 
incapable of exciting chemical action, They doubtless 
Undergo transformation into heat in the deeper structures. 
This action may readily influei and 

isive drainage of the deeper tissues. It is in turn fol- 
lowed by marked sedation, which can readily be accounted 
I'm- by the sudden and intense drainage through the skin 
of the accumulated products of the disturbed chemico- 
action of the system. 

The Action of Incandescent Light Energy in Health. — 
The action of these baths was studied by E. Rosen 1 
healthy men. Follow i ries of \2 of these radiant heat 

baths, a marked improvement of appetite and sleep was 
noted I gain in weight. These favorable 

changes seemed to he lasting. Then ... a numerical 

increase, now a diminution of the cells according to R 

peutic Indications for an Expenditure of Incan- 
;i i ight Energy. — Incandescent light baths have been 

J Ku»ks Vr.'ilcli, \l:irvh ( (903. 


found useful in conditions of i i j lowered nutrition, the 
acid dyscrasias. rachitis, osteomalacea. (2) in the lipogenous 
dyscrasias, obesity, biliary lithiasis. gravel, diabetes, ar- 
thritic manifestations of gout and rheumatism, (3 ) in altera- 
tions of the blood state, anaemia, chlorosis, lymphostasis and 
syphilis, (4) in nervous conditions, tabes, neuralgias, hys- 
teria, psychoses, (5) in respiratory and circulatory condi- 
tions, bronchitis, bronchial asthma, cardiac hypertrophy, 
(6) in diseases of the kidneys, nephritis, (7) in surgical 
conditions, chronic tul>ercular ulcers, inflammatory diseases 
of bones, chronic leg ulcers, paralysis and trophic disorders, 

(8) in toxaemias, alcohol, drug and metallic poisoning: 

(9) as a hygienic measure. In some of these conditions 
they form the remedy par excellence, in others an ex- 
hibition of a light energy more profoundly chemical in its 
action is indicated, i.e., solar light or electric arc light 
energy. The indication for the one or the other is pointed 
out as far as is possible, but there only need to be kept 
always in mind the nature of the energy and its action, in 
connection with the nature of the condition, in order to 
choose intelligently the one or the other. Incandescent 
light energy may take the place of the other two to a certain 
degree if the individual equipment contains but the one 

The Therapeutic Effects of Incandescent Light Energy. 
— (1) There is established by the action of these baths a 
profound action on the vaso-dilators of the arteries. P>y 
the stimulation imparted to them the blood is permitted to 
flow more rapidly to the surface. In this way the heart is 
relieved of its burden, and. at the same time, the constric- 
tion to the arterial circulation and the capillaries is also les- 
sened. From this action there ensues lowered tension of the 
blood stream with an increase in its volume and uniformity. 
A marked effect upon sensory centres is noted, as is evidenced 
by a diminution of nerve irritation and debility. 

(2) There is established a profound revulsive effect by 
the dilatation of the cutaneous vessels. For the time being 



the blood is fixed in the skin, the "peripheral heart." In 
tins way passive venous congestions are connected with 
active arterial hyperemia. 

(3) Profound action upon die sweat glands with corre- 
sponding elimination activi 
led oxidation. 
Th< tits from these effects a return to normal skin 

ity 8 norma] circulation and oxidizing power upon the 
part of tlu- organism. The general tone is increased and 
with it physiologic resistance. 

Preparation of Cabinet and Patient. — The first depends 
upon whether it is desired to secure the sudden effect of 
erful lighl action. This would be indicated in robust 
ns and for such the cabinet should be heated before- 
hand. The sudden impact, as it were, of this radiant heat 
at high temperature imparts a greater stimulus, just as 
, erful static spark does. In weaker and more fragile 

patients thi air of the cabinet musl be heated gradually after 
the patient is placed therein* The temperature may be 
gradually increased by switching in additional lamps or 
adding to the amperage by means of the controllin 

The patient is placed naked in the vertical or horizontal 
cabinets OH a Stool or slab of glass, A towel may be placed 
about file neck to prevent the passage of the heated air or 
light from the enclosing cabinet, A cold bandage, ie< 
coil of coed water is applied to the head. 

The condition of the pulse must be carefull] observed 
and the admission of fresh air to the patient cared for, 

Duration of Treatment. — These baths should be used 
for varying periods of time according to the effect desired. 
When the object to be attained is that of sudation or tran- 
spiration, the lunger exposures and the use of all the lamps 
within the cabinet are necessary. Where a tonic effect only is 
desired, however, then a ven short exposure, and a fewer 
number of lamps, i.e., diminished energy of radiation. For 
the first purpose from 15 minutes to 30 or in conditions call- 


ing for profound action even longer. For a simple tonic 
effect from 3 to 5 minutes suffices. 

Frequency of Treatment. — Here, as with other measures, 
the nature of the case must influence at least the frequency 
of the treatment. In some conditions and for a limited time. 
daily baths may be given. Where profound eliniinative 
effects are desired this may be done and also for the promo- 
tion of absorption of inflammatory exudates. Hut, as a rule, 
the need for daily exposures will he met by the first 3 to 5 
treatments. After that from 3 times, twice to once a week. 
Too frequent an expenditure of energy is as harmful as too 
prolonged an expenditure. The needs of each individual 
patient must be conserved by the skill, experience and care of 
each individual operator. 

After Treatment. — This should assume the form, of a 
bath, douche or wet pack. 

It may be further supplemented by mechanical measures, 
as massage, vibration or by the use of the electric current. 
Each case will present its own indications, the rationale of 
it all being to use such a measure as will best assist in secur- 
ing a return to physiologic circulatory conditions without 
overtaxing the patient. 

Feeble patients should always rest for shorter or longer 
periods of time. The author believes that the best good if 
the patient is attained by a period of rest immediately after 
the expenditure of any form of energy. This applies to 
those who are frankly ill, not to robust patients who use 
this form of light energy as a hygienic measure. As a 
hygienic measure incandescent light baths are of value. This 
fact is taken into account occasionally in the fitting up of 
men's clubs. Such a light bath from once to twice and three 
times weekly for 5 to 10 minutes, followed by a bath, or a 
short plunge at from 65 to 75 F.. or a vigorous douche at 
a temperature of from 50 to 60 F. will amply repay the 
individual. In the conservation of the physical forces and 
the prevention of disease there is to be found after all the 
physician's highest work. 



Incandescent Light Energy in Obesity, — In the use of 
these baths in obesity there must only be considered (i ) the 
pathological nature of the condition, and ( 2 \ the physiologi- 
cal action of light energy from this source, to appreciate at 
once its very great value in this class of eases. Obesity is 
fundamentally a condition of sulfoxidation and imperfect 
eliminative pr Moreover, it is apt to be associated 

with grave dietetic and hygienic errors. There is not oidy 
the powerful action of incandescent light energy, when thus 
concentrated upon the sweat glands, but there i^ as well a 
profound and penetrating action upon the deeper structures 
of the skin, and of the tissues of the body as well. As a 
result nutritive as well as eliminative changes are estab- 
lished. A considerable part of the light energy thus ab- 
sorbed is converted into heat, which serves to stimulate to an 
unusual degree the consumption of fat, as is evidenced by 
increased carbon dioxid elimination. 

According to ECellogg, there is more than 40 per cent, in- 
crease in tissue consumption* This in view of the fact that 
at least three- fourths of the energy of the body is consumed 
in beat production becomes a matter of the highest im- 

By an expenditure of this light energy over considerable 
periods of time, an hour or more, there would result a con- 
siderable loss of fat. 

Conrad Kkr 1 has shown that the heat elimination may be 
increased to more than ten times the normal amount and that 
it may he continued not only for a few moments but OVOT 
considerable periods of time, when the temperature of the 
air surrounding the patient is below the temperature of the 
body, provided that the blood vessels are maintained in a 
state of active dilatation, as is possible with an incandescent 
light hath but in no other heating procedure. 

Win tern itz has observed after one such bath followed 
by a douche, that the weight has diminished from 700 to 800 

'Physiologic Therapeutics, Cohen. 


grams. Eiffer. Ga:n:er and Irr.ben .:e !e Touche have ob- 
tained equally satisfactcry resets without enfeebling the 
patient or obliging hits to submit to debilitating dietetics. 
The bath need not in such cases be of high temperature. 
98.6 : F., 37 = C- Winternitz has observed the appearance of 
perspiration at a temperature not above 86 F. or 30- C 
While care should be taken in patients where cardiac func- 
tion is enfeebled, still even with them these baths are very 
well borne. There is usually an acceleration of the pulse but 
it remains full and regular. 

Chasserant 1 records a case where it was a question of a 
mixed form of obesity, in which by an unimportant restric- 
tion in the regime, combined with incandescent light baths, 
there was obtained at the end of about 6 weeks a diminution 
in weight of 25 pounds. In another case, where it was a 
question of the constitutional form, the patient although 
always eating little had continued to increase in weight. 
She had tried to limit the amount of food to the strictest 
minimum without any result. Incandescent light energy- 
was prescribed in the form of the cabinet bath to be followed 
by massage, without modifying her normal regime. At the 
end of 40 days, during which time she had taken 38 baths, 
there was a diminution of 30 pounds in weight. For 6 weeks 
treatment wa? discontinued, during which time she increased 
5 pounds in weight. Further treatment for 2 weeks resulted 
in a loss of 10 pounds. While it is best to combine the 
expenditure of some other form of energy, hydriatic 
measures, electricity, massage or physical exercise with the 
expenditure of incandescent light energy in these cases, still 
there is no question but that in the case recorded the diminu- 
tion in the weight should be attributed to the action of the 
incandescent light energy, for experience has taught us the 
futility of massage to reduce the weight in the sanu* class 
of cases. 

Treatment of Obesity by Baths of Electric Light. Rev. cle 
Therapent. March, 1902. Rev. Internationale d' Gleet rotherapie et 



The diminution of weight in these cases is more or less 
according to the amount of perspiration. This is usually 
mpanied by extreme thirst (not alone in obesity, hut in 
all classes of cases where prolonged exposure to intense in- 
candescent light energy is employed ). which if satisfied may 
counteract to 3 certain extent the good effect. The dietetic 
regime should therefore receive attention. 

According to Strasser 1 this form of light euer- 
dally suited to the hydremic forms of obesity, particularly 
the anaemic, pasty-looking type found in young people. For 
the plethoric type of corpulent patients he prefers packs. 

The temperature of these baths may vary from the mini- 
mum to a maximum, which differs with different operators. 
Kellogg" lias placed it at from 150 I*, to the highest tem- 
perature tolerable. It is reported that some French ob- 
servers have employed a thermometer the bulb of which ; 
covered with lampblack, a great absorber of heat, which is 
also fully exposed to the action of the thermally active 
energy by being placed upon the patient's body. Ther< 
their measurements are he relied upon. 

According to Strebeh the temperature should never ex- 
ceed U3°h\ for this class of cases, The author regards this 
a safer temperature, but each case must after all govern 
itself. There are some obese patients who will withstand a 
very considerable expenditure of light and other forms of 
energy ; while on the other hand then are those whose en- 
durance in this regard is limited. 

The Influence of Incandescent Light Energy upon Gout 
and Rheumatism, — Perhaps incandescent light enerijv dues 
not lend itself to the securing of better results in any other 
class of cases than these. There is obtained from these 
baths in both gout and rheumatism rapid relief from pain 
and other symptoms. The exposures may he either general 
or local or general supplemented by local where especial 
joints are implicated. A certain discrimination is required, 

'Blatter f. klin. Hydrother. 1900. No*, 4, 5. p. 94. 
*Kellogg: System of Physiologic therapeutics, Cohen. 


however, in their use. In gouty patients it is not always well 
to call too severely upon the fluids of the body, as a thorough 
transfusion of the tissues with fluid is desirable. Under 
these circumstances and also in rheumatic affections of the 
joints, a light energy less active thermally and more active 
chemically is indicated. To this end either the energy of 
solar light or of the electric arc should be used. In muscular 
rheumatism, lumbago and torticollis, incandescent light 
energy is of very great value. I>y its use there is increased 
elimination of toxic material and the promotion of oxidative 
processes. In these cases the bath should be given every 
other day, at first to the point of producing vigorous per- 
spiration and an elevation of the body temi>cratiire 2 or 3 
degrees. Daily exposures may be indicated in the beginning, 
but should not be continued so often for too long a time. 
They should be given from daily to three times, twice or once 
a week as the case progresses. The general bath should be 
given from 3 to 5 minutes, or longer, according to the indica- 
tions in the individual case. 

The after treatment in this class of cases should prefera- 
bly be a cold plunge 65° to 75 °V. If this is not available a 
very excellent substitute may be found in a cool bath or cold 
towel rub. Again the needs of the individual must be met as 
they rise. Routine treatment is never successful. 

An expenditure of electrical energy will materially aid 
the progress of this class of cases and may be made by a 
general application of the magneto-induced sinusoidal, 
static or high frequency. The two latter are very efficacious 
and the preference is apt to be given to them, as the clothing 
offers no obstacle to their use. 

The Influence of Incandescent Light Energy in Rheu- 
matoid Arthritis. — Friedlander 1 found that the electric light 
(cabinet baths) gave better results than Turkish or Rus- 
sian (steam or hot air chamber) baths. Jn the treatment 
of this disease, the two last named are objectionable because 

'Haiulbucli Der Physikalisclien Therapic, Teil II.. Bassel I., 
Leipzig. 1902. 


( i ) they with difficulty admit of | <sagt\ (2) They 

have here a weakening effect, and they make a serious de- 
mand oil the circulatory system. 

There is no question hut in an expenditure bi radiant 
energy much better results would follow in rh 
arthritis than from any other expenditure of thermal energy. 
I lent results are secured in these cases from the use of 
static electricity administered convectively, disruptive! 
e< inductively, according to the needs of the individual 
The author hclieves that the well-known helpful action of the 
electrical treatment would be enhanced by n preliminary ex- 
posure to incandescent light energy. Great care should he 
taken not to prolong the light hath unduly nor to permit 
too intense a temperature. The minimum exposure and 
minimum temperature at which perspiration is induced 
should he the rule until the patient's toleration is fully estab- 
lished. This the author follows by the electrical treatment 
as above, preferably to anj other physical measure, save the 
necessary rubbing clown ( 1 ) with alcohol or (2) with the 
cohi mil ten, according h> the indications and only for a 
period of time necessary to thoroughly dry the skin. 

The influence of Incandescent Light Energy upon Dial»e- 
tes. — In this class of patients the aullmr yields the preference 
to the electric arc because of its deeper and more intensely 
chemical action. Still there is considerable evidence to show 
that incandescent light baths are useful 'And when ju 
used they may take the place of the electric arc. where the 
equipment affords but the one, just as the exhibition of one 
drug may take the place of another in the absence of the 
first. An exception 01a \ he made preferably in favor of the 
incandescent light hath in fat diabetics. They are especially 
likely to !>e favorabh aftYvied by these baths. Under the 
powerful Stimulation of the light energy, thermal and chemi- 
cal, the inactive skin becomes active and free perspiration is 
established. The well-known oxidating action of the light 
results in an increased oxidation and a lessened excretion of 
sugar. An increase of the alkalinity of the blood is but a 


part of this process, but one that is of value in the correction 
of this perversion of nutritive action. There may be expected 
in the average case a relief of symptoms. The after treat- 
ment, hydriatic, massage, or electrical, must depend uj>on 
the individual case. Prolonged exposure at a considerable 
temperature should be followed preferably in all cases by 
cold douching. 

The Influence of Incandescent Light Energy in Anaemia 
and Chlorosis. — Excellent results have been obtained in 
these conditions by the use of the incandescent light baths. 

Save in fat anaemics and chlorotic patients the energy 
of the electric arc or of the sun is to be preferred because 
of the greater quantity of penetrable chemical frequencies 
and their absorption by the blood. In fat anaemic patients 
the radiant heat bath, by reason of its intense thermal activ- 
ity, is to be preferred. This class of anaemic cases do not 
do well until they are rid of their superfluous flesh. After- 
wards the progress of such cases should be furthered by the 
use of the sun or electric arc baths. An increase of haemo- 
globin and erythrocytes was observed in anaemic persons by 
Winternitz after each bath. The more profound effect of 
the chemical frequencies in producing lasting hyperaemia 
and pigmentation with a removal of the blood corpuscles 
from their ordinary course, stimulating the system to re- 
place the blood corpuscle, and the more vigorous carrying 
on of the metabolic processes renders solar light and electric 
arc light better in anaemia and chlorosis, and, for that mat- 
ter, in all conditions involving an alteration of the blood 

It was noted by Kellogg that the increase in the blood 
count, red cells especially, in anaemics was permanent where 
the bath was used daily. The temperature of the bath 
should not exceed 05 ° to I04°F. (35" to 40 °C.), and the 
time of exposure should be short, stopping when transpira- 
tion begins. 

After-Treatment. — A tempered douche, either jet or rain, 
or a short tepid bath should follow. 

4 2C 

lh;ht energy. 

i^ntra-lndications. — There are practically none. 

The diaphoresis and the consequent thirst secures the 
ingestion of considerable quantities of water, which favors 
normal osmotic processes and facilitates the removal of 
waste material or toxic agents, which serve to prevent nor- 
mal oxidation and tissue change. 

The Influence of Incandescent Light Energy in Nenri 
Diseases. — Incandescent b reported to h 

found useful in a considerable range of functional nerve 
disorders, but in the author's opinion they are not com- 
parable in this class ■ -» i" rase- (■< the electric arc bath or sun- 
hath. An exception may he made in Eavor of tl 
lomatic neurasthenias where the disturbed nerve function is 
due to toxaemia or autointoxication. Certain hysterias 
and epilepsies more of less dependent upon a 
tion should he benefited by their use. They have been 
widely recommended in neuralgias ol all sorts, and for the 
physician having but the one equipment, can be used in all 
these functional nerve disturbances, but the preference 
should be given ( i) to the solar energ nergy 

of the electric arc. There is a considerable variei 
opinion among different writers as to the value of incan- 
descent light energy in functional dif I the no 

My some their ^ I effects are lauded, their soothing effect 

on general irritability, sleeplessness, singing in the i 
oppression im<\ palpitation of the heart, as noted by Col- 
ombo, for example. The difference in opinion doubtless has 
its explanation in ^discriminative diagnosis. Good results 
will follow the use of these baths in functional nerve dis- 
turbances, which are not essential but symptomatic and due 
to a toxaemia. Colombo reported excellent results m all 
vague neuralgias due to the so-called "uric acid diatlv 
An essential neurasthenia is not a suitable condition tor 
these baths, but, as has been stated, does well under the 
influence of the electric arc. \euralgia and migraine, Kel- 
logg, Strehel and Kretind relieved by incandescent light 


When used in motor troubles and muscular atrophy, re- 
education in movement, mechanico-therapeutic gymnastics 
and electricity should be used in connection with them. 

It was observed by Foveau de Courmelles 1 in 1893 that 
the total white light from incandescent lamps exercised an 
anaesthetic and calming effect when directed upon the nerve 
centres, spinal cord, and he used it combined with the static 
douche in the treatment of neurasthenia. Later the same 
observer found the incandescent light bath, in which the 
patient's body was placed, with the head only emerging, an 
excellent tonic to the spinal cord, and of service in the treat- 
ment of myelitis. 

In the author's experience a neurasthenic patient, whose 
condition was complicated by severe spinal congestion, and 
who suffered not only from insomnia, but from intense pain 
at the roots of the cervical nerves, had relief from the ap- 
plication of an incandescent light bulb directly over the cer- 
vical cord. Sleep without hypnotics was only obtained in 
this way, the patient sometimes leaving the light burning 
all night, because of falling asleep under its influence. 

The Influence of Incandescent Light Energy in Respira- 
tory Diseases. — Reider 2 states that incandescent light baths 
afford good results in chronic bronchitis, and in bronchial 

In so far as these conditions are dependent upon the 
so-called lithaemic diathesis they should be benefited by 
them. But for all diseases of the respiratory system as such, 
the electric arc or solar light is preferred. 

Cardiac Hypertrophy and Cardiac Dropsy. — The same 
observer obtained good results in these conditions from the 
use of incandescent light baths. Kellogg states that in his 
experience the bath must be used with a considerable degree 
of caution in this class of cases. The temperature should be 

Report of Light in Nervous Therapeutics, by Foveau dc Cour- 
melles, Revue Internationale d'filectrotherapie et de Radiotherapie, 
Jan., 1904. 

*Quoted by Kellogg, System of Physiologic Therapeutics, Cohen. 

4 28 


I'u at first, increased very gradually, and high tempera- 
tures alu idcA The heart must be guarded by ice 

or a cold precordial coil placed in position before the light 
is turned on. The application should be brief, barely suffi- 
cient to induce gentle perspiration. Cold mitten friction 
should be applied immediately afterwards, and care taken 
to prevent chilling by exposure alter the bath. The cuta- 
neotu acttvit} From the action of the radiant heat, with the 
precautionary measures suggested; greatly 
burdened heart by diminishing the distension of the right 
ventricle, b) lessening the resistance in the peripheral 
sels, and by setting at work the skin-heart," which is often 
BlOSl inactive in those conditions* 1 

In grave cardiac conditions, sun baths or the electric arc 
bath are to he used preferably, as, for example, in valvular 
heart disease. The same is ti lions of the venae 

port*, angina pectoris, and in difficulties of breathing. 
They are not only more edevtive, but do not possess the 
same element of danger for this class of cases as incau 
cent light energy. 

The Untoward Influence of Incandescent Light Energy 
upon the Heart. — Krebs 2 has observed that it would be an 
error to believe that incandescent light energy in the form 
of baths has no effect Upon the heart. In almost all cases 
studied by him he has observed that the profuse secretion 
of perspiration produces accentuation of the pulse and dim- 
inution of the blood pressure, hul the increase of the fre- 
quency of the pulse in equal conditions of rest was less 
great than in the bath of superheated air, This is corrob- 
orated by Medley. Although the bath of incandescent light 
energy is more grateful and better borne by the patient w 
heart is feeble, yel Krebs believes it not to be without dan- 
ger for patients having organic lesions. 

'Physiologic Therapeutics, Kellogg. 

"Diaphoresis bj Electric Light Baths and Superheated Air. 
Zeitschrift fiir Diiitetische und Piiysikalische Therapy, Bd VI*, H. 
21, No. J. 


The Influence of Incandescent Light Energy upon 
Arterio-Sclerosis. — Incandescent light baths, while of much 
value in arterio-sclerosis, are unsuitable in extreme cases. 
They should be administered with great care, the heart's ac- 
tion and condition of the circulation carefully watched. If 
there is not prompt reaction upon the part of the skin, as 
evidenced by perspiration from the earlier baths, they are 
contraindicated. The temperature of the bath and the length 
of the exposure should be governed by the individual case, 
and also the after treatment. In the author's judgment the 
minimum temperature and length of exposure are indicated. 
The condition of the blood vessels must not be lost sight of, 
their rigidity and inability to accommodate themselves to too 
intense or too prolonged thermally active energy. After 
treatment in this condition would better assume the form 
of an alcohol rub or cold mitten friction. This in turn may 
be followed to the advantage of the patient by the convec- 
tive discharge from an excited influence machine. 

The Influence of Incandescent Light Energy in Nephri- 
tis. — Because of the fact that the incandescent light bath 
produces abundant diaphoresis without materially augment- 
ing the w r ork of the heart it is of service in all albuminurias. 
It is not that they affect the cause of the trouble but that 
they relieve the symptoms which interfere so much with the 
comfort of the patient. There is, however, prompt relief 
affprded to the congested and inflamed viscera by the diver- 
sion of from one-half to two-thirds of the blood in the body 
to the skin. These baths, according to Kellogg, may be pro- 
longed for many hours if necessary (the condition of the 
patient must govern both the length, frequency and tempera- 
ture), but care must be taken to refresh the patient at 
intervals by a very energetic cold rub with a friction mitten, 
by an ice-bag over the heart and by cold compresses to the 
head. Great care must be taken to avoid chilling. A slight 
exposure of the body to the influence of evaporation from a 
moist surface might be sufficient to cause contraction of the 
blood vessels and counteract the good effects of the bath. 



Immediately after the bath, the patient should be wrapped in 
flannds and preferably placed in bed. 

Frequency and Duration of Treatment.— This latter is 
placed by Kellogg at from 4 to 6 hours and to be repeated in 
fn»m 24 to 36 hours. Cases of this sort must be guarded 
against too great an expenditure of energy. 

By reason of the fact that incandescent light baths pro- 
duce but a temporary hyperemia of the skin and therefore 
only temporary depletion of the interna! organs, the\ are of 
less value in diseases of the viscera, where circulator) drain- 
age is necessary i than the more penetrable chemicalh active 
energy of the electric arc and of sunlight. Still in their 
general ability to produce safely profuse diaphoresis the in- 
candescent baths are desirable, When there has been secured 
copious sweating better results should follow the use of the 
electric arc bath. The indications for beginning the latter 
would be the same ;is for the suspension of other agents used 
to promote diaphoresis. 

Bj the use of both incandescent and electric arc baths 
different observers have noted a diminution in the amount 
of albumen. 

I ' mitra-Indications — Uremic Crises. — In conditions of 
cardiac weakness great care must be taken and the condition 
of the heart's action carefully watched during the progress 
of the bath. 

The Influence of Incandescent Light Energy in the 
Toxaemias. — Whether the condition is that of an autointoxi- 
cation, metallic poison, alcoholism or drug habit there is to 
he found in incandescent light baths the best possible elimi- 
native agent. There is secured by reason of the profound 
sudation the ingestion of water in considerable amounts 
which acts as an internal tissue lavage and by its absorption 
promotes normal osmotic as well as chemical action. The 
drainage of the deeper tissues facilitates the throwing oil tin 
accumulated residue of toxic material. At the same time 
the tonic action of the light energy with associated hydnatic 
measures tends to the establishment of a different fimda- 


mental condition on the par. •.:" these ra::e::ts. There is 
secured a better f:unda:::n :n the case ■:■: alcho-ics and 
drug habitues upon which to build in ::>:::£ specific drug 

The Influence of Licht Energy in the T xr::.i> and 
Toxic Neuroses. — Nothing car. ;* m re important than the 
fundamental drainage and washing clean, as it were, the or- 
ganism of all its accumulated impurities. The action of incan- 
descent light energy in this class of cases is illustrated in sev- 
eral of the cases reported by Dr. T. D. Crothers 1 at the 1003 
meeting of the American Electro-Therapeutic Association. 
Crothers. from a series of a thousand baths in toxic neuroses 
and in the palsies, found them of the very greatest Vnefit. 
He finds that they are to lie preferred to hot air and vapor 
baths, which he former!;. i:> t -d fir the same class of cases. 
In the toxic neuroses, under which he mentions the various 
influenzas and digestive tr"i:Mes indicated by irritation, de- 
pression, headache, irregular heart action and other forms 
of obscure nerve manifestation^, he found the incandescent 
light baths of the greatest !>enefi:. When associated with 
appropriate hydriatic measures Ik- finds them of greatest 
benefit in what he terms the general palsies under which he 
mentions the neurasthenias, cerebrasthenias. the multiple 
palsies and defects of the motor and sensory centres, where 
nerve vigor, force and energy are disturbed and depressed 
below the normal, also in many of the conditions following 
a deranged cerebral circulation with defective nutrition, the 
vaso-moti>r facial paNies. >■» common among drinkers, were 
also favorably influenced, fr-ni a modification of the condi- 
tion to complete recovery. In these anomalous cases, he 
used in conjunction with the radiant energy of baths the ci in- 
vective discharge from a static machine, mechanical mas- 
sage, vibration, hydriatic measures, according to the case. 
Saline waters were administered before the bath when indi- 
cated. These cases reported by I 'rot hers are mentioned in 

'X. Y. and Pliila. Med. Journal. July jj. iqoi|. 


this connection rather than under the head of nerve disor- 
ders, for the reason that they are the new toxemia 
and as such lend themselves admirably to incandescent li^ht 
-y. Nerve disturbances not v_> induced, neurasthenia 
essentialis and locomotor ataxia, for example, need the chemi- 
cally active energy of the sun and electric arc. 

Case L — An active business man in middle life suffered 
from fainting and dizzy sensations following excitement and 
OVer-exertiofl. The heart was hypertrophicd and the arterial 
tension was high, indicating hardening of the arteries. He 
was given electric light baths daily with hot showers and 
douches and the static breeze. This treatment was followed 
in recovei 

Case II — A business man of alcoholic habits, whose life 
had been one of great mental strain and worriment, came 
under his care for asthmatic symptoms associated with 
den depressive heart action. A course of Turkish baths had 
failed to bring relief, and he complained of dizziness with 
fluttering heart sensations, for which various forms of 
alo 'holic stimulants were given. The alcohol was with- 
drawn and the patient put on an active saline treatment. The 
radiant light bath, followed by showers and douches and 
constant rot in a reclining position, was given. The bath 
produced intense prolonged sudorific action with a high 
surface temperature. In some instances this t emper ature 
went up 3 or 4 degrees, but quickly dropped under 
the influence of showers and douches. The pulse rate de- 
clined with each bath and the fluttering heart symptoms 
disappeared. Later the heart centres seemed to be very 
greatly disturbed, and as in the morning be complained of 
chills and cold lie was taken to the light bath for a few 
minutes, being taken out before perspiration began. The 
regular bath was given in the evening, after which he slept 
quietly. There was evident toxaemia in this case, indicated 
by the strong acid odors from the perspiration during the 
first week of treatment. A static breeze was given every 
day in connection with the bath. He made a good recovery. 


Case III. — A lawyer, 35 years of age, had used spirits 
for relief from insomnia and the fatigue of overwork for 
many ye^rs. He had been under the care of many physi- 
cians, and had taken electrical treatment with a variety of 
drugs, but had gradually grown worse. Spirits and drugs had 
been taken alternately for years. After preliminary treatment 
by salines and the withdrawal of spirits the use of radiant 
light bath was begun. The perspiration was not very intense 
at first, but the action of the heart was increased. The tem- 
perature dropped from one to two degrees. On each suc- 
ceeding bath the pulse rate was raised from 10 to 15 beats 
and the temperature lowered. At the end of a week all 
drugs were dropped and the bath was given daily. The rest 
after the bath was very refreshing and increased in duration, 
until finally he could sleep about 8 or 9 hours. The insomnia 
passed away and the restoration was rapid and complete. 

Case IV. — A physician, 50 years of age, who had suffered 
a severe electric shock 5 years before had from that time 
drunk spirits steadily to quiet his nervous system and to 
promote rest at night. He had an intense fear and dread of 
electricity in every form and had strong delusions that he 
would be injured by an electrical current in some unknown 
way. For some time after coming under care he refused 
to take radiant light baths, using the hot air bath and receiv- 
ing the shower and massage afterward. Perspiration was 
induced slowly and but little change in the temperature fol- 
lowed these baths. He finally consented to take a radiant 
light bath, remaining in only 3 or 4 minutes at first, just long 
enough to cause slight perspiration. It was found that his 
skin was over sensitive to the action of light, and intense 
perspiration broke out in 4 or 5 minutes after admission with 
a high surface temperature. The shower afterwards reduced 
his temperature. The heart's action was raised, but fell 
quickly from the action of showers to normal. A marked 
sedative effect followed these baths with the disappearance 
of the electrical delusion and a rapid improvement mentally. 
A persistent dyspepsia, which had followed him for many 



disappeared and he recovered and is now at work 
again in bis profession. 

Case \\ — A medical man, neurotic and a gourmand, had 
been alternately a drug-taker and spirit-user for mam 
At times he would abandon them all and live for months in 
strict abstinence. He was credulous and had great confi- 
dence in drugs and used freely many prescriptions, b<»ih 
proprietary and other combinations. He had taken electrical 
treatment and had been an inmate I 2 sanitariums without 
receiving much benefit. On admission lie was using par- 
aldehyde 4 times a day and was considered a chronic 
briate. All drugs were withdrawn, and he was given the 
electric light bath twice a day. remaining in the cabinet until 
perspiration vva> very profuse, then taken OUt, showered 
and put to lied. The temperature was invariably lowered 
and the pulse was raised by the hath. Later on the first 
morning bath was confined to 2 or 3 minutes, while the 
evening bath was continued to or 12 minutes. The surface 
temperature of the body was 105° and io6°F. after leaving 
the cabinet, but rapidly went down to normal after the 
showers. The condition of the arteries improved, and both 
the bowels and kidneys acted quite freely after the evening 
bath. Later, the static breeze was given, before the bath and 
sometimes after. With improved nutrition the nervousness 
disappeared and restoration followed. 

The Influence of Incandescent Light Energy on the Ab- 
sorption of Exudates. — These baths have been used with 
good effect upon chronic exudations and effusions. Es- 
pecially have they been used in E ranee for promoting the 
absorption of exudates in the cornea of the eye and vitreous 
opacities. Keratitis parench\ m atosa, iridocyclitis, choroiditis 
and Other conditions of a similar pathologic nature are ni> 11 
Honed by Freuiuk Kellogg states that he has used incan- 
nt light energy with most gratifying success in the 
absorption of exudates in the pleural and peritoneal cavities, 
and in and about the joints, From their general and local use 
combined with appropriate Mydriatic measures, absorption of 


exudates in and about joints is rapidly stimulated, and the 
author questions if there is a better means to the end. The 
treatment of joints need not necessarily be confined to in- 
candescent light energy. On the other hand, the electric arc 
with a parallel beam converged to a focus on the affected 
joints in long-standing processes should yield better results. 
In this way not only the necessary thermal energy is pro- 
vided, but an intense chemical energy as well of great pene- 
trating power. 

Contraindications. — Contraindications are found in or- 
ganic heart disease, and marked congestive symptoms, in 
phthisis with night sweats (the author advises the use of 
the electric arc or of sunlight in all cases of phthisis, and 
never under any circumstances uses the incandescent light 
in this class), in hemorrhagic cases, haemoptysis, haemateme- 
sis, apoplexy, and in all cases where no perspiration results 
from the earlier baths. 

Other contraindications may be found to exist either in 
other pathological conditions or in individual cases, the 
rationale of which will appear from the fundamental prin- 
ciples of the action of incandescent light energy in connec- 
tion with physiological action, and its relation to the especial 
pathological manifestation. 


he Concentrated Visible Chemical Frequencies of the Solar 
Spectrum. Mechanisms, Mith. and Therapeutic Indi- 

cations, M il L^Tiiiiit Pustttlt, Diphtheritic Croup, Pneumonia, 
Pulmonary Tuberculosis and Lupus Vulga 

The Concentrated Visible Chemical Frequencies of 
the Solar Spectrum. 

In the visible chemical frequencies of solar light theft 
are to he had in great abundance the very penetrating and 
valuable blue-violet frequencies. These, when concentrated 
and used in such a manner as to eliminate in part the intense 
thermal energy of solar light, can la- tised in a considerable 
variety gt morbid conditions. In fact, they are useful in 
every condition to which light is applicable. Inn not as use- 
ful in deep-seated localized skin conditions, lupus vulgaris, 
for example, as the electric arc light, becattse of the slight 
chemical intensity in the ultra-violet region at the earth's 
surface, as compared with that artificial source of light, and 
also because With a simple convex lens, not only the light 
energy hut the thermal energy as well is gathered into a 
fOCttS. In this focus so high a temperature is generated 
that it is simply impossible to expose living matter to it for 
any length of time. It is only necessary in this connection 
to recall one's youthful experiences with the burning glass 
for the purpose of ignition ; or, to still further emphasize the 
fact of this intense thermal energy; to instance the burning 
of the vessels of the Romans before Syracuse by Archimedes. 

The Use of a Parabolic Mirror to Prevent Undue Heat- 
ing. — It is noted that as the red or thermal frequencies arc 
less refrangible than the frequencies above the red, they may 


be eliminated to a certain extent by means of a parabolic 
mirror. For this purpose only the reflected rays of the sun, 
not the direct as per the method of Finsen are used and these 
refrangible rays are condensed and focussed on the patient in 
the usual way. 

Concentrated sunlight is obtained by using ( i ) convex 
lenses, or (2) concave mirrors. 

Many years ago the burning glass was used for the pur- 
pose of concentrating sunlight upon the affected part. From 
its use in this manner good results were obtained. In con- 
nection with such use there may be mentioned the names 
of Butler, 1 Thayer, Mehl, Piffard, and a layman mentioned 
by Otterbein. 2 

Willard" states that within his recollection Butler in the 
sixties, some 40 years since, successfully employed sunlight 
for the treatment of epithelioma using for the purpose an 
ordinary biconcave lens. 

Piffard 4 is authority for the statement that he employed 
sunlight, concentrated by means of a glass lens, about 25 
years ago, for the treatment of a few cases of lupus. By 
this means the lesions were simply burned out, as in con- 
centrating the light of the solar spectrum by a glass lens, 
the thermal frequencies are extremely active. Every one is 
familiar with the action of concentrated sunlight through 
a glass lens in the ignition of inflammable material. This 
action was the same in Piffard's original work, as there is 
no mention of any filtering arrangement for the exclusion 
of the thermal activities, as in the case with the hollow lens 
filled with a solution of sulphate of copper as used by Finsen. 

The Sun Lens as Used by Finsen. — The solar condenser, 
as devised and used by Finsen at his institute in Copenhagen, 
consists, first, of a hollow plano-convex lens, 25-30 cm. in 
diameter, with a focal distance of 60 cm. It has a capacity 

'Quoted by Willard, Sunshine vs. X ray. Jour. Am. Med. Ass., 
July 18. rox>3. 

"Quoted by Finsen. 


*N. Y. Med. Record. March 7, 1903. 



of about 2 liters, and was filled with an amnion ical solution 
of cupric sulphate* flic object of the copper solution is 
to absorb not only the thermal frequencies, but all save tl 
having the same refrangibilitv as the corresponding color 
of the spectrum, This lens is mounted on a foot in such a 
ua\ as to enable the operator to give it a vertical, horizontal, 
as well as an up-and-down movement at will. All the fre- 
quencies then from the edge of the blue to the ultra-violet 
region, none less than 30 microcentimetres, however, in pass- 
ing through this lens are condensed, and foeussed at a 
point of about 60 cm from it. In this way there is pro- 
vided a greatly condensed luminous sheath of practically 
pure chemical frequencies other than the ultra-violet. 

These frequencies are possessed of a germicidal action, 
as is shown by the action of sunlight on bacteria and upon 
polluted streams. 

The Purely Bactericidal Frequencies not Present in Con- 
densed Solar Light. — The purely bactericidal region as 
shown by the experiments of Bernard and Morgan, however, 
is not present for two reasons ; ( 1 ) That but few of the short 
high frequency waves of light, ultra-violet are present in 
sunlight at the earth's surface, because of their absorption by 
the atmosphere, and (2) the glass of the condensing lens 
effectually absorbs such as there are. A lens so filled witn 
cupric solution does not completely eliminate the thermal 
activities, and it may he necessary, therefore, to ha 
second lens, which is used as a compressor to dehematize 
the tissues, also made hollow with two canulae, one afferent 
and one efferent, in communication with the cavity. Through 
this a current of cold water was kept constantly passing. 
Because of the prolonged exposures necessary with con- 
densed sunlight in the treatment of organized skin condi- 
tions, the solution in this second lens also becomes hot, 

\Y. II. Dalphe 1 states thai with this second heat filter 

■W. H. Dalphe, B.A.. MR: Light as a Therapeutic Agent, 
lecture delivered to ihe students nf the class in Pharmacologj 
Therapeutics, University of Bishop's College. Faculty of Med 
Mon 1 real March, 1903. 

Fig. '5- — Sun Lens. 


has been obliged to interrupt his sittings and that through 
it he could set fire to paper or cotton goods in a very short 

Methylene blue is sometimes used in the. large hollow- 
condensing sun lens as a filter of the longer slower frequen- 
cies below the blue. A solid lens, with or without a blue 
glass filter, may be used, either in connection with a circu- 
lating water glass filter, which is independent of the lens, or 
without it. 

Photographic Ray Filter for Concentrating Solar Light. 
— Kime 1 used a modification of the ray filter employed in 
photography, with an 18-inch focus. At the focal point it is 
intensely hot. but he found that in some cases nothing short 
of this intense heat established reparative processes. This 
was by reason of the fact that 1>oth the source of Iicrlit « sun 1 
and the means used 1 glass \ ab>orb the very valuable and 
more intense chemical frequencies ultra-violet, s-i neces-ary 
in combination with the blue-violet in establishing :i->ue 
reaction and securing the regressive and productive tissue 
changes essential tM the reparative process. In hU work he 
utilized a beam <.f sun>hinc one f«»ot in diameter, which fell 
through the • ffice window upon the sun glass, the h !!v.v 
chamber of which \va> nTed with a *oh::i n ••! *r.*phate of 
copper for the p::rp-»-e <\ absorbing the fr-r.:er.o:e- ^'//.v 
the blue. 

Not a": »■■: th- <" n:> r.-r.: Par:- '■: V.':::*- Light ~\n r^e 
u-e-: with a St:r. L-:>. — ' if--: rr. r- :-. "h> r :.::--. r. it rr.ay 
m 'x reiterate! that r. ■ r - • : **■ ■•■: -\trv. : '.- ■: ' *■' - y rr.: - •-.- 
ti—vtr-r- car :a- tr.r -.' *" - _-V« '• -\' : -r"- -r '■-•?-'- 



sorbed by passing through 2.5 cm, of water There is still 
further absorption by the addition of methyl blue or an 
amnion iacal sulphate of « 

Ultra- Violet not Transmitted through Quartz Contain- 
ing Chamber when billed with Ammonia-Cupper Sulphate 
Solution. — Under proper conditions of experiment, i.e. t with 
a quartz containing chamlier for the ammonia-copper sul- 
phate solution, 5%, through which the beam of light is 
allowed to pass upon examination by means of a grating 
spectroscope, it is shown that blue, indigo and violet fre- 
quencies pass, but practically no ultra-violet. However, as 
with the glass containing lens, the ultra-violet are cut off in 
any event, the blue filtering solution docs not interfere with 
the residual en erg j of the risible chemical frequencies of the 

Were it practical to have sun lenses made of quartz, then 
by filling them with uncolored water there OQttld be obtained 
a greater proportion of the non-absorbed (i.e.. by the atmos- 
phere) of the ultra-violet frequencies than with a blue filter- 
ing fluid. But because of the scarcity and expense attendant 
upon the quartz lenses, this is not practicable. It is clearly 
shown in these pages, however, that valuable as the ultra- 

Hold frequencies are ( 1 ) in bactericidal power and ( 2) abil- 
it\ tn excite tissue reaction, they are not absolutely essei 
to the obtaining of therapeutic results in skin conditi 

I nicies early work with the sun lens wa> demonstrative of 

this fact. If ultra-violet energy be of low intensity, it is 
absorbed lw ihe surface layers of the skin, but if of higher 
intensity, a vtolenl inflammation <>f the skin is produced. See 
Action of Light Energy Upon Skin, Chapter VII. 

This intensity of ultra-violet light energy is such as is ob- 
tained ftom iron electrode arcs, for example the original 
Hang lamps, or those modelled by it. 

The Complex of Chemically Active Light Energy Pro- 
duces the best Results, — Under the use of the concentrated 
chemical frequencies of the electric arc it is clear!) p tinted 
out that the penetrant blue, indigo and violet frequencies are 


factors of great importance where deep-seated processes are 
to be acted upon, that their presence is more necessary than 
the ultra-violet, but that, after all. it is the complex of 
chemically active light energy which is capable of producing 
tht best results. 

If the thermal energy is sufficiently eliminated by the 
filtering arrangements for that purpose, it is not possible to 
produce so intense an inflammation upon the healthy skin 
with concentrated sunlight as with the electric arc, by reason 
of the absence of the ultra-violet. 

In the adjustable photographic ray filter used by Kime 
there is at the focal spot intense heat which produces, a 
strongly irritant action upon which he depends for the exci- 
tation of the necessary reaction, i.e.. the production of 
hyperemia inciting in its turn new vigor, new cell action, 
and subsequent reparative processes. This action is duo to 
the combined influence of the concentrated thermal and 
chemical energy. 

Concave Mirrors for Concentration of Solar Light. — A 
greater quantity of light can be concentrated by means of 
concave mirrors than can be done by lenses. Kime has util- 
ized this fundamental principle in the construction of his sun 
room at Denver for the treatment of tuberculosis pulmonalis. 
Strebel also uses metal reflectors one metre, $).$ inches, in 
diameter but with a water-cooling arrangement in front of 

Technique. — The technique with the sun lens is the same 
so far as preparing the lesion for cxp isrre as with anv 
source of light, viz.. freeing the diseased surface from 
crusts. In addition, in Kime's work the part was washed 
with water, but no antiseptics were used. This is a matter 
which varies with the individual operator. The light is 
moved over the tissues, coagulating the albumin in the tis- 
sues, until it is of a smoky white color. The light is used 
at the focal point for this, and the action desired is secured 
in a few minutes. This application should always be made 
by the physician himself, but afterwards for the subsequent 



and prolonged application of tin- light, non-focal, it mav be 
left in the hands of the nurse Of office attendant, who con- 
tinues the application for 10 minutes longer, A wet di 
ing is Mien applied, to be removed the following morning, 
when a 20-tninute exposure is made at the non-focal point 
of the condensed light. On the third day Kime uses the 
light again at the focal point upon any part which has 
tailed to respond to its irritative influence. The parts are 
thoroughly cleansed twice a day. fn his monograph on the 
subject Kime Submitted lour photographs showing most ex- 
cellent results. 

Recapitulation, — Treatment with a sun lens while capa- 
ble of securing extremely good results, is not so good as 
with an electric arc. 

The concentrated visible chemical frequencies of solar 

light energy are useful in all of the skin conditions in which 
the electric arc has been found to he oi service as set forth 
in Chapter XI L, The Concentrated Chemical Frequencies of 

Electric Arc Spectra, The difference in effect is in d< 
not kind, and when the thermal em concentrated 

light is sufficiently eliminated from the latter, it is differ 
due to the greater proportion of the ultra-violet in the arc: 
a difference which is. however, compensated for to a consid- 
erable extent by the richness of the solar Spectrum m the 
blue- violet frequencies. 

Concentrated chemical solar light energy can also be n 
in Suppurative and septic processes, as can the electric arc. It 
is a question only of the flexibility and adaptability of the 
means to the end, Experimental work and clinical evidence 
suggest that it is not as good in syphilitic lesions as the con- 
centrated chemical energy of the electric arc. The same use 
of solar light winch happily cured a tubercular laryngitis 
as quoted, failed in a case of syphilitic laryngitis It is 
quite possible the author believes that the same hippy result 
would have followed the use of a source of light rich, in 
ultra-violet frequencies in this case. This point is fully 
elucidated ifl discussing the treatment of syphilis under the 


concentrated invisible chemical frequencies of the spectrum 
or ultra-violet light energy (Chapter XVI.). 

The literature of the therapeutics of concentrated and 
condensed chemical solar light energy is not as rich as that 
of the therapeutics of artificial sources of light, but the 
individual operator in possession of a sun lens will find that 
in practical work he may closely approximate by its skilful 
use the results obtained with the electric arc. 

Treatment of Suppurative Keratitis by Solar Light. — 
Among those who have experimented with the sun lens may 
be mentioned E. Xesnamow. 1 ' I lis experiments were upon 
artificially provoked suppurative processes in the cornea. He 
used a concentrating lens similar to Finsen's, of 8 diopters 
and 10 cm. in diameter. Care was taken to exclude the 
thermal energy. 'Five severe ulcers of the cornea were 
treated for 2-5 minutes daily with the blue- violet frequencies 
of solar light with excellent results. To exclude the thermal 
energy Nesnamow filtered the light through a layer of water 
colored with methyl blue. 

Concentrated Chemical Solar Light Energy in Tubercu- 
lar Laryngitis. — M. Romme 2 quotes a rei>ort of M. Sorgo 
to the Society of Internal Medicine of Vienna, in which the 
latter reports the case of a patient with well-characterized 
tubercular laryngitis. He concentrated solar rays, by means 
of the laryngoscope, upon the ulcerated mucosa of the larynx. 
At the end of 30 seances of this laryngoscopic phototherapy, 
of which each had a duration of about an hour, the vocal 
chords had recovered their normal color, and the tubercular 
ulceration was cicatrized. 

The healing of a tubercular laryngeal nicer was estab- 
lished in the author's experience in two weeks without any 
direct application of the light activities. In this instance, 

^Vcstnik Ophthalmologic. 1901, Jan. and Feb. cf. Dworctzky 
Zcitschr. s. diat. 11. Phys. Th.. Vol. V. Part III., also Anier. Med., 
May 31. 1902. 

^Desiccation and Phototherapy in the Treatment of Granulating 
Wounds, by M. Romme. 

Revue Internat. d'filectrothcrapie ct Radiothcrapie, Jan., 1904, 
abst. from Presse Medicale. 



cer. the electric arc was used, giving the maximum of 
ultra-violet energy. In the latter there are available many 
more of the intrinsically valuable chemical frequencies, and 
as a source of light it is much more flexible and amenable to 
control than sunlight. The latter is uncertain, not only hid- 
ing y< ies oftentimes when needed, but also 
Use of one's inability to control the position of the beam 
of light, and hence its focal point in a sitting of any length. 
Often, at least rtn hour is required for a sitting, and this 
means constant attention on the part of the physician or his 
assistant, as the lens will have to be continually moved, verti- 
cally, horizontally and up and down. It is a tax upon the 
physician's time and the patient's endurance and patience. 
But in the absence of i source of E. M. I*\, rendering il 
sible to Use an electric arc, it is eminently worth while. Its 
advantages conpensate for its disadvantages. It is portable, 
can be used at a patient's house, as well as at the physician's 
office, and is well adapted to a country practice. In latitudes 
where the sun is but little obscured by clouds, as in the more 
southern climes, it is pre-eminently useful. 

In this field Kime has been an indefatigable worker, a 
brief resume of whose methods and results in the use of 
concentrated chemical solar light energy (l) by means of 
the sun lens in skin lesions and (2) by the use of reflecting 
mirrors in tubercular pulmonarv lesions is given, 

The Concentrated Energy of the Visible Chemical Fre- 
quencies of the Solar Spectrum in the Treatment of Lupus 
and Other Chronic Skin Affections, — Kime 1 prefaces a re- 
port of a series o: 1 rated bv means of solar light en- 
ergy, and the manner of its use b ut that "light 
and especially concentrated actinic light derived from the sun, 
is a specific in the treatment of lupus, chronic ulcers, and 
other destructive lesions of the skin." 

The Concentrated Energy of the Visible Chemical Fre- 
quencies of the Solar Spectrum in the Treatment of lv.1- 


Jotfroal nf the AniLTicm Medical Association, April ii. 


monary Tuberculosis, Concentration by Means of Mirrors. 
— Kime has also contributed two very valuable papers upon 
this subject. In the last 1 one, after calling attention to the 
physical characteristics of light energy and its physiological 
action, he gives the following description of his method for 
utilizing sunlight in pulmonary tuberculosis : A concave re- 
flector, 36 inches in diameter, overlaid with blue glass, 
focuses a strong blue light upon the surface of the chest, 
made bare for two hours each day. This light is sufficiently 
strong to thoroughly illumine the lungs. Patients thus 
treated (using all other adjuvants of known value in the 
treatment of tuberculosis), Kime finds respond more quickly, 
and a greater percentage of recoveries takes place than under 
any other method of treatment with which he is familiar. 
Even cases far advanced begin to show improvement almost 
immediately, and from his experience he is convinced that 
but few cases in their earlier stages may not be permanently 
arrested. This statement is made from a personal experi- 
ence of a number of years, and is based upon a sufficient 
number of cases to warrant its truth. 

Since his first report Kime has removed to Denver, 
where he has a maximum of sunshine. There he has his 
skylight constructed of blue glass, but the reflectors are not 
overlaid with it. 

The following is the order in which improvement occurs : 
loss of chills and night sweats ; gain in body weight ; in- 
creased appetite; lessening and disappearance of diarrhea 
if it is present; increased strength, as a rule, rapidly, and 
ability to walk considerable distances as against short dis- 
tances before: diminishing cough without the use of medi- 
cines; declination of febrile conditions in from a few weeks 
to 2 months or more, and after 2 or 3 months a return to the 
normal, where it remains. Bacilli are almost the last evi- 
dence of the disease to disappear, as they were also the first 
factor in the production of the disease. Frequently patients 

'New York Medico! Journal and Phila. Mid. Journal. April .*o. 



leave the sanitarium with bacilli still remaining, and when 
they return a few months later the bacilli are found to be 
absent from the sputum. 

The concentrated energy of tin solar spectrum does not 
seem to have been availed of to such an extent by any one 
person a> by Dr, Antonio Sciascia. In his published work 
Sciascia 1 used an instrument of Ins own device to which he 
gave the name of FotocautcruK His instrument is designed 
for the condensation of the chemical and thermal energy of 
solar light. The lenses are of glass, biconvex, therefore, 
so far as the chemical energy is concerned, it is the visible 
chemical frequencies only which are used. But as few in- 
visible or ultra-violet frequencies are available in solar light 
it does not so much matter. By the use of different sized 
lenses, from l to 4 e/ern. in diameter, areas of varying size 
were treated, and by the interposition of different colored 
glasses, the energy of one part or another of the spectrum 

was used ai will, li is also capable of regulation as to 

focal distance so that the focal spot may be used near to the 
apparatus or projected at a greater distance, according to 
the condition to be treated. Because of the wide and un- 
usual range of diseases subjected by Sciascia to the action 
of "lar light energy, the care with which his cases are re- 
ported, and the results obtained the author has thought best 
to introduce them into this text to stimulate and guide 
Others in their work. 

There is found in a personal experience corroboration 
of much of Sciaseia's work. To secure the same results re- 
quires an intelligent, skilled and patient use of the energy 
of solar light, with which southern climes especially are so 
bountifully provided by nature. 

From iS<kj to ill jit time Sciascia has been able to 

record 28 cases of malignant pustule, more or less serious, 
all cured by the action of light energy. The following cases 
are types of the series : 

ototer&pia, Roma Soci£t£ Editrice Dante Aiighieri, tgoa, 


Malignant Pustule — Case I. — A. C 2S years old, a 
shepherd of sound constitution : has had no sickness worthy 
of note. 

Presents a pustule upon the left cheek, dating about 4 
days. In the centre of the same is a necrotic area. 3 milli- 
metres in diameter, surrounded by a number of vesicles of 
various sizes J from a hemp seed to ? pea ». The cutaneous 
tissue which surrounds the pustule i> in a condition of acute 
tumefaction, which extends to the Ixumdary of the face and 
on the neck, as far as the supra-clavicular fossa of the same 
side. Several days before he fell sick he had skinned a 
sheep dead of carbuncle. About the third day of his sick- 
ness he became feverish. He was sick and livid, prostrated 
with fever — T. 39 T C. P. 120, R. 42. The local lesion tended 
to diffuse with rapidity, causing an impairment of the gen- 
eral condition. 

Treatment — First day. — Exposure for one hour of the 
diseased area to the concentrated and condensed energy of 
solar light. ( The thermal energy was utilized as well as 
that of the visible chemical frequencies. — The author.) 

During the luminous projection the rupture of the vesi- 
cles begins with the discharge of a turbid whey, and the 
vascular cutaneous rete becomes swollen ; by degrees the 
more delicate capillary vessels dilate, the swollen cutaneous 
tissue from livid becomes rosy, and begins to exhale a moist 
vapor, visible to the naked eye, with gradual reduction of 
the swelling, the local pain is relieved, and the temperature 
is diminished. 

Second Day. — An eschar is noticed at the necrotic point, 
it extends but more superficially at the site of the vesicles 
destroyed the preceding day. At the periphery of the new 
necrotic area are seen some new phlyctenules much smaller 
than the former. The swelling is much reduced, the pain 
relieved, the fever reduced. The action of the second appli- 
cation of the solar energy is the same as on the preceding 

Third Daw — A limitation of the eschar is noticed; no 



appearance of new vesicles The carbuncle-like swelling 
is much reduced, less pain, no m r. The action of 

the third application was like tlfat of the preceding. The 
exposures were repeated for 10 more days, at which time 
repair had taken place with disappearance of the eschar. A 
small tmnotice&bk scar remains. 

Case II. — A woman. 60 years old, In addition to having 
a lacerated Contused Wound upott the forehead is reported to 
have handled the flesh of animals dead of carbuncle. After 
10 days a malignant pustule appeared in the same locality 
as the wound, appearing like a scar. 

Clinical Rep€>rt. — On the pre-existing wound is observed 
a gangrenous eschar, with some small carbuncle-like ves 
at the periphery, full of a turbid, bloody whey ; the face is 
invaded by oedema; acute pain is experienced especially in 
the left orbit-palpebral region near the pustule. The patient 
is feverish, T. 38.5°C. 

Treatment' — First Day. — Deep cauterization of the pus- 
tule with the solar energy. 

Second Day. — -The patient is without fever; the 1 
inflammation is much improved; the carbuncle-like eschar is 
limited, the vesicles entirely destroyed, 

Third Day. — The improvement of all the symptoms is 
progressing; the necrotic crust begins to separate at the 
periphery, and the action of the light energy is like the pre- 
ceding day 

Pour more applications of condensed white light, Tern. 
. on alternate mornings are sufficient to produce a defi- 
nite cure, 

I ase III. — A shepherd, aged 40, presents a carbuncle- 
like eschar on the left forearm, dating since 7 days, of round 
shape, diameter 2 cm., with some small phlyctenules near the 
periphery. The inflammation extends through the entire 
arm, the axillary lymphatic glands of that side are swollen 
and painful Patient is feverish, Temp, 3,8°C. 

Treatment. — One deep cauterization with concentrated 
solar light, at the maximum degree of temperature on the 


malignant pustule was sufficient, with a daily application of 
white condensed light, T. 50°C. and a complete cure was 
obtained in 20 days. 

Case IV. — G. G., 18 years old, shepherd. No previous 
illness. Ten days after he had skinned a goat dead from 
carbuncle, a pustule developed below the left labial com- 
misure, where a small ulcer pre-existed. He treated the 
matter as though it was nothing, neglected to consult any 
physician, although by the fourth day he was feverish. 
Nevertheless he waited two more days, ''trusting to the help 
of nature/' 

On the sixth day he came under observation for the first 
time, and was in a "condition of great embarrassment. ,, 

The pustule is surrounded by phlyctenules of various 
sizes. In the centre is a necrotic area of the diameter of a 
centesimo (the coin equal to the size of an old-fashioned 
American cent), which invades the entire thickness of the 
tissue as far as the oral cavity. The swelling is acute and 
painful to pressure, extending over the face and neck. The 
oral mucosa which surrounds the eschar begins to resent the 
spread of the process. The patient is cyanotic, drowsy, in a 
state of collapse, with cold extremities. The respiration is 
stertorous, pulse almost imperceptible, T. 36°C. 

Treatment — First Day. — In a dangerous condition, and a 
fatal result imminent, it was therefore necessary to have a 
recourse to more energetic medication than usual, namely, 
photo-cauterization of the pustule and to make a distribu- 
tion within the carbuncle-like seat of inflammation of the 
vapor of iodine, to impress with more facility the auxiliary 
therapeutic action of the iodine and to push the iodine in a 
gaseous state through the circulation. Moistening then the 
pustule with iodine, an application was made with the photo- 
cautery, which allows the maximum concentration of solar 
light to the moistened necrotic eschar, to an area of half a 
centimetre. A sufficient temperature was used to cauterize 
the pustule deeply, and to vaporize the iodine. The rupture 
of the phlyctenules with the discharge of a turbulent san- 



guinolent whey was also produce* I The alimentation is by 
rectum, consisting <d milk, eggs and coffee. 

cottd Day. — The pattern responds to all questions; can 
swallow, his pulse is somewhat raised. T. 30,.3'C The 
eschar extends [ess deeply, as far a> the site ot the destroyed 
vesicles; the swelling, redness and pain are much reduced. 
The application o! chemical condensed light for an hour 
obviates the necessity for farther photo-cauterization. Dur- 
ing the luminous projection the patient noticed a local com* 
fart with relief of the pain. 

Third Day. — No fever, everything is relieved. The 
necrotic tissue is beginning to detach at the periphery. The 
action of the usual application is the same until the totli day, 
when there is a detachment of the necrotic tissue. A sinus 
remains which communicates from the outside with the oral 
cavity, the borders of this are granulating. With the con- 
tinuation of the light energy until the 30th day there was the 
healing of the sinus and the small cicatrix seen in the photo- 
graph. These 4 cases are photographically illustrated in 
the original. pictoriaKy vouching in every instance for the re- 
sult obtained. 

Pertussis. — Dr. Sciascia has also recorded 60 cases of 
pertussis, 50 children and 10 adults, all cured by the use of 
o nulensed light energy, I le has observed that the condensed 
light acts as an antispasmodic and shortens the duration of 
the illness. Two illustrative cases are given : 

Case I. — S, G M 3 years old, is harassed with pertussis in 
the convulsive period. It was the 15th day of the disease. 
The prodromk period occurred with fever and symptoms of 
simple bronchial catarrh, lasting for 10 days. 

Clinical Report. — The child is without fever, hoarse, 
panting, with swollen face and ecchimotic spots under the 
conjunctiva. The crises of the convulsive cough were in 
classical form, occurring 12 to 16 times in the 24 hours. 
They were of long duration with frequent vomiting. The 
nose was filled with a thin sanguinolent liquid; the mucosa 
of the vaso-pharyngcal-epiglottic cavity was hyperamic; in 


the right supraclavicular fossa were felt nodular kernels 
of various sizes which extended deeply near the thoracic 

Treatment — First Day. — Application of chemical con- 
densed light, in an area which uniformly irradiated the face, 
the neck and the chest, producing an abundant sweating and 
frequent sneezing with epistaxis. The child cried under the 
stimulating influence of the condensed light, and this pene- 
trated the pharynx without the need of a tongue depressor, 
producing a hypersecretion of the thin mucus. 

Second Day. — Nothing new is observed. Exposure 
to the light energy is repeated for an hour, as on the preced- 
ing day, producing the sweating and sneezing without epis- 

Third Day. — A great amelioration was observed. The 
crises of the pertussis begin to be more rare, and without 
vomiting. The same method was continued for 8 more 
days and a definite cure of the pertussis and the resolution 
of the engorged glands was obtained. 

Case II. — A girl of io years was brought in after 20 
days of the sickness, harassed with an obstinate pertussis 
with grave symptoms. The prodromic period was about 10 
days, with fever, and simple bronchial catarrh. The physi- 
cian had exhausted the arsenal of rational pharmaceutics 
without result. 

Clinical Report. — The child is anaemic, ill-nourished, 
sunk in a profound languor, tending to inanition. The fits 
of convulsive cough are in classical form, frequent and of 
long duration. The naso-pharyngeal-epiglottic mucosa is 
hyperaemic, with adenopathy of the right cervical region ex- 
tending to the supraclavicular fossa of the same side. 

Treatment. — Application of chemical condensed light in 
the pharyngeal region, with the tongue depressed, which 
produced an abundant secretion of mucus, and profuse 
sweating. An application of the same strength which in- 
cluded the face, the neck and the anterior part of the thorax 
was made for an hour. After two days a cessation of vomit- 



a mitigation of the fits of convulsive coughing with an 
amelioration of the other symptoms was noticed. ! 
other sittings were sufficient to produce a complete cure of 
the pertussis and the resolution of the engorged glands. 

Tuberculosis. — In several forms ol tubercular lesions, the 
results were excellent. 

Lymphangitis Tuhercnlo-< iiimmatosa. — <». S., 18 years 
old, with positive hereditary antecedents She had a torpid 
nodular swelling at the articulation of the left elbow. She had 
trusted for her treatment t<» the ill-advised exercises of a 
poor ignorant woman of her country) a serious maltreatment 
complicating a phlegmonous, suppurating periarthritis, 
which opened spontaneous!) on the external part of the artic- 
Eilatiofl with a discharge of pus and caseous detritus, accord- 
ing to the report of the attending physician. At that time 
there was left an incurable opening* 

I linical Report — The disease elated from 7 months. The 
young woman was emaciated with fever. She presented a 
torpid ulceration at the articulation of the left elhow, antero- 
external region, periarticular, extracapsular with flabby 
i, thick and full of lumps and with different subcuta- 
neous Sinuses which extend to the middle of the forearm. 
The morbid process tends to spread in the periphery and 
deeply. Moreover, at the lower part of the sternum in the 
vicinity of the Xiphoid appendix a little to the right is ob- 
served a tuberculous gumma, the size of a dove 1 
which is beginning to soften. The overlying skin is reddish 
ami tends to thin out. 

Treatment. — To fill up the ulcerated cavity at the elbow 
with a powder of iodine mixed with potassium iodide, and 
with the photoeautery project the maximum concent r; 
of the sun's rays to heal the powder of iodine, producing an 
azure light with the developing of iodine vapor while deep 
cauterization occurs. 

The tubercular gumma on the chest was treated with 
the photor.mterv, until the production of an eschar. This 
detached itself after the second day with discharm- of a thin 


yellow liquid mixed with caseous detritus. Then the cavity 
was filled as usual with powdered iodine, which was treated 
by the photocautery to produce a deep cauterization down to 
the sound tissue. This operation was repeated 3 times with 
an interval of 20 days, besides 20 sittings with chemical 
condensed light. After 3 months the cure was complete. 
The articulation of the elbow remained unhurt. At the end 
of 5 years it has not relapsed. 

Tubercular Poliadenitis. — V. M., 10 years old, with bad 
history. Presents a chain of glands which occupies the 
right cervical region to the supraclavicular fossa of the same 
side. The glandular kernels are of various sizes, from a 
pea to an almond; some are swollen, others caseous or 
ulcerated. The morbid process tends to spread with the 
appearance of new glandular nodules of the same kind in 
the neighboring organs. The general condition shows a 
progressive wasting. 

Treatment. — Local application of an area of chemical 
light for an hour a day. Sixty sittings are required to 
obtain a cure. 

Observation. — The glands in the condition of simple 
inflammatory swelling came to full resolution ; those that 
suppurated became caseous and ulcerated. On account of 
the cicatrization they are destroyed and eliminated more 
slowly by a natural work of a morphological process, in 
the same way as the eliminations of tuberculosis and lupus. 

In 12 other individuals affected with the same disease 
Sciascia obtained the same result. 

Tubercular Peritonitis. — M. L., age 9 years. Etiol- 
ogy positive,. was a case of tubercular peritonitis treated suc- 
cessfully by means of concentrated light energy. The patient, 
a child, presented the classic symptoms as well as typical 
physical signs. There was anaemia, ascites, enlargement of 
the abdominal lymphatic ganglia, vomiting, anorexia, vague 
abdominal pains, intestinal disturbance, scant urinary secre- 
tion with trace of albumin. 

A general application of the light was made to the entire 



abdominal and thoracic region for an hour on alternate 
days. Gradually after three months there was resolution of 
the ascites and enlarged lymphatic ganglia, with improved 
nutrition, After five years the patient was still well. 

Pneumonia, — In 12 cases of croupous and catarrhal 
pneumonia, good results are reported. A typical case is 
the following : 

Lobar Pneumonia. — D. \\. a countryman 40 years old. 
Presents a pneumonitis of the superior lobe of the right 
lung dating from 4 days, with general symptoms of adyna- 
mia. Upon auscultation is heard an accentuation of bron- 
chial breathing. Upon percussion an area of diskless IS dis- 
covered in all the region of hepatization of the lung; the 
cough is frequent with difficult expectoration of a prune- 
colored secretion. T. 40 (.".. P [JO, R. 40; the urine is 
loaded with urates, and contains albumin, the compensatory 
respiration is impeded by collateral c edema. 

Treatment. — Daily applications of chemical light in the 
right region of the thorax for half an hour; afterward pro- 
voking the nasal reflexes with the thermic light energy. 
T. 52C. to facilitate the expectoration through the re- 
action upon the "fibroid cellules of the lung/' By the third 
day the hepatization begins to resolve, the crepitant rattling 
to return, heard in the posterior part. The cough is less 
frequent with easier expectoration. The fever is less, 
T. 38 C, and the collateral cedema has disappeared. At 
the fourth sitting, after the crisis of a copious sweating the 
defervescence of the fever occurred and complete resolu- 
tion of the pneumonitis. There remained during the con- 
valescence a mild pulmonary catarrh, which was not of long 

Diphtheritic Croup. — Six cases were treated by the con- 
densed light energy, with recovery. 

Descending Diphtheritic Croup. — V. L. t 5 years old. No 
previous sickness worthy of note. 

Clinical Report. — The sickness has lasted 3 days with 
fever, malaise, pain in the throat, and difficulty in swallow- 


ing. The mucous membrane, which covers the tonsils and 
palate, is covered with false membrane, the nose discharges 
a yellowish serum, sometimes bloody ; the neck is invaded by 
a swelling; the urine contains traces of albumin. On the 
fourth day a hoarse cough developed with progressive rest- 
lessness and shortness of breath. 

On the fifth day there was dyspnoea, suffocation, supra- 
clavicular depression on inspiration and threatened asphyxia 
with an imperceptible pulse. 

Treatment — First Day. — Application of chemical con- 
densed light to the naso-pharyngeal-epiglottic region, caus- 
ing a hypersecretion of mucus to facilitate the elimination 
of the false membrane, reduced to a pulp by the action of 
the light. There is sneezing with epistaxis. In conse- 
quence of the sneezing and the sweating the respiration be- 
comes freer, and the general symptoms are relieved. 

Second Day. — The false membrane is not reproduced, 
the fever is milder, the cough is less; the circulation and 
respiration improved, and the glandular engorgement tends 
to resolution. Six other applications of the light energy 
were repeated on alternate mornings, gradually producing 
a cure. A slight degree of hoarseness and a catarrhal cough 
remain for two weeks. Six other cases of equal seriousness 
were treated with the same method, recovering in longer or 
shorter time. 

Nervous Diseases. — In chorea minor, Dr. Sciascia has 
treated 20 cases with success, 16 girls and 4 boys, from 6 
to 15 years old. Neuralgias and hysteric conditions are also 
reported as cured. Typical cases are given in detail : 

Chorea Minor. — A. C, 13 years old, a peasant. 

After prodrome of the disease with psychic disturbance 
he was taken with incoordinate, involuntary movements, 
especially on the left side. 

Clinical Report. — The sickness dates from 6 months. 
Shows irregular motions of the head, of the muscles of the 
face, and of the limbs; sometimes a contraction of the ex- 
tensors, at other times a flexion and raising of the shoulders. 


The patient is not able to stand on bis feel on account of 
the manifold incoordinate movements, which complicate 
3 or 4 groups of muscles in different regions at the same 
time, and cannot be controlled by the will. He stammers 
and slights his vowels, and eats with 3 convulsive motion. 
Sensibility to heat and pain is diminished in the left 1 

Treatment. — Application of an area of chemical con- 
densed light which includes uniformly the head and ver- 
tebral column for an hour, producing a copious sweating*, 
and relief from the spasmodic action Ten other applica- 
tion were sufficient to obtain gradually a definite cure. 

Sciatic Neuralgia : Basedow's Disease. — M. C. f 37 years 
old, multipara, of weak constitution, habitually neurasthenic. 

For 6 moiuhs she has been harassed by pain in the left 
side. At first it prevailed principally in walking, now it is 
insupportable during repose. 

Clinical Report — Presents exophthalmia, hypertrophy of 
the thyroid and tachycardia. The pain is paroxysmal and 
obstinate in the left thigh, accentuated during the night with 
phenomenal intensity. The points of pain are sacro-iliac, 
trochanteric, popliteal and malleolar, Lasegue's sign exists. 

Treatment. — Every kind of medical treatment had been 
employed "with discernment" in the treatment of the sciatica 
without result. 

First Day. — With the solar energy the work of cauteriz- 
ing trascorrentt (running over), according to Valleix. 
the first time, and then the daily application of chemical con- 
densed light of a uniform area, which comprehended the left 
lumbar, popliteal and mall- ;ions for an hour, alternat- 

ing the thyroid body and the cervical ganglion of the sym- 

Even- application produced copious sweating with pro- 
gressive alleviation of the pain, gradual decrease in the 
paroxysm until the thirtieth sitting: after that she had a 
definite cure of the sciatica ami a relief of the cardiac symp- 
toms depending Upon the Basedow's disease. 


Tic Douloureux. — I. C, 57 years old, healthy. For 4 
months he was affected with an acute pain, spasmodic and 
insupportable in the lower part of the left cheek in the labio- 
mental region. 

During the attack every slightest movement in speaking 
and chewing, or the lightest touch upon the point of pain, 
was impossible. No movements or other manoeuvres oc- 
curred in the intervals of pain. The objective examination 
shows that the seat of the trouble is in the third branch of 
the trigeminal nerve, at the exit of the inferior dental nerve. 
The cause of the hyperalgesia is the irritation of the mental 
plexus and the fibres of the facial which cross it, resulting 
in the clonic muscular contractions which complicate the 
neuralgia. The spasmodic pain is acute, frequent and rebels 
against all pharmaceutical treatment. Neurectomy is ad- 
vised. For this the eminent surgeon, Dr. Carlo Gangitano, 
Professor of Clinical Surgery in Naples, was called. Be- 
fore he intervened and the last resource was exhausted, the 
patient was sent to Sciascia's Institute for Phototherapy. 

Treatment. — One the first day the photocautery, i.e., 
thermic solar energy for the work of "passing over" (Tras- 
corrente) cauterization according to Vallei, in the painful 
region of the inferior dental nerve was used, followed by 
the projection of a chemical condensed light over the spas- 
modic zone for an hour. This produced a profuse sweating 
and a general sense of well being. The spasms returned 
during the day with the same intensity, but less frequently. 
On the second day there was no need of photocauterization. 
With the repetition of the light chemical condensed treat- 
ment of the preceding day, a progressive amelioration was 
obtained, until the tenth sitting, and a complete cure was 
obtained. Thus the surgical operation was avoided, which 
would otherwise have been necessary, because the patient 
could not longer endure the pain of the sickness. 

Peritonitis. — Two cases of peritonitis were treated with 
the condensed chemical light, with complete recovery of 



ise L — If. N., 26 years old, multipara, of good con- 
dition. For 6 months she had suffered with acute spas- 
modic pain tn the abdomen, with frequent vomiting, hic- 
cough, ami vesical spasm. 

Clinical Report.— There is a marked meteorism, with 
lancinating; pain in the whole abdomen. It is impossible 
to make the least palpation on account of the painful spasm 
which it causes ; the patient is unable t<> hear a light covering. 
Vomiting is frequent, micturition is spasmodic with the emis- 
sion of clear normal urine* The pulse is small and quick, 
the respirations short, with frequent hiccough. All these 
symptoms are accentuated in the early morning hours, with 
convulsive twistings of the patient. 

The aesthesioineter reveals a zone of hyperesthesia in 
the left side. 

Treatment. — Narcotics, emollients, warm baths, and all 
those things which are indicated for entero-peritonitis are of 
no value. 

An application of chemical condensed light was made to 
the whole abdominal region for an hour. It produced a 
copious sweating with alleviation of the spasmodic symp- 
toms. The pain in the early morning hours returned with 
its usual crisis, but with symptoms of less severity. She IS 
able to bear slight manual pressure upon the abdomen with- 
out inconvenience. The phototherapy was repeated like that 
of the preceding day. with an amelioration of the general 
and local condition. 

After two other 1 exposures to the action of the chemical 
condensed light, she obtained a complete cure. 

Five years have gone by without return. 

Case II. — In a case of orrhymenitis (peritonitis) in a 
young woman aged 18, multipara, there was an exudative 
peritonitis with fever and gastro- intestinal disturbance, 
After a month a cough came on with dyspnoea, thoracic pains 
and haemoptysis. 

Clinical Report.— The illness was of 40 days* duration. 
She presented a pleuritic effusion in the right side. The 


liquid occupied two-thirds of the thoracic cavity. The 
semilunar space of Traube had disappeared, the pericardium 
and the abdominil cavity showed a separate effusion. The 
distention was very great, as shown in the photographic 
illustration, and the countenance bore the expression of pain 
and distress. The patient was anaemic, badly nourished, and 
had febrile disturbances. Intense lancinating pains, retro- 
sternal, interscapular and abdominal were experienced. 
There was cyanosis, an angina, hiccough, vomiting and dis- 
ordered cardiac functions. 

The concentrated light was applied by Sciascia on every 
alternate day for one hour upon the thoracic-abdominal 
region. Fifteen exposures were made in all. The first 
treatment was followed by copious sudation, a sense of well- 
being, and alleviation of pain. The patient made a complete 

Sciascia also reports one case, each of abdominal typhoid, 
gastric ulcer, arthritis Menorrhagia, and puerperal metritis, 
in all of which good results were obtained from the applica- 
tion of the condensed solar energy to the region of the lesion. 
A series of psychical conditions are also reported. 


The Concentrated Energy of the Electric Arc Spectra, Car- 
bon, Carbon and Iron, Iron. Mechanisms, Methods of Use and 
Therapeutic Indications. Finsen. Lupus Vulgaris, Lupus 
Erythematosus, Sycosis, Eczema, Tubercular Ulcers, Tubercular 
Glands, Neuritis, Neuralgias. 

The Concentrated Energy of the Electric Arc Light 
in Skin Diseases. 

The most important use of the concentrated chemical 
frequencies of light in skin diseases, in a certain sense, is in 
the treatment of lupus vulgaris. In the last report of his 
Light Institute at Copenhagen, Finsen 1 gives a resume of. 
800 cases treated. In these 800 cases there was improve- 
ment in 90%, cure in 70%, reappearance in 20%, the latter 
heing generally cases where the mucous membrane was in- 

The following table gives a detailed analysis of the 800 
cases : 

i. Apparently cured 407 j H 2 S ;;;;;;;; ['l~ 6 ***** [- 51* 

II. Nearly cured 193 24* 

III. Marked improve- , nA norfll . > 

IV. Not sufficiently (14 not permanently ) 

treated 40 < 12 . .some improvement .- Improved $% 

( 14... n< 

>•< 12. .som 


.negative result ) 
( 33 — died 

III. Dismissed 71 -j 13— sickness 

( 25— did not return for treatment 

'Mitteilungen aus Finsen's Mediciniske Lysinstitut in Kopenha- 
gen. 1904. 


Finsen is of the opinion that not more than 2% of 
tubercular lupus cases can be regarded as incurable. 
And Bie has said that a failure of a case to respond to 
the action of light energy is an indication of a wrong diag- 

As the arc light mechanisms in use for therapeutic appli- 
cations to localized areas are arranged (1) to concentrate 
all the energy of the arc by means of reflecting mirrors on 
the area to be treated, and (2) not only to concentrate but 
to condense the energy of the arc by means of condensing 
or focal lenses, as in the Finsen and Finsen-Reyn apparatus, 
the author has chosen to consider both methods under the 
single head of the concentrated energy of the electric arc, 
for such it is in both instances, but in the latter condensed 
as well. 

In the text, therefore, wherever the means to the end is 
referred to as the concentrated energy of the arc, there is 
to be understood the full energy of the arc concentrated, by 
means of suitable mirrors, to a beam of lesser or greater 
diameter, according to the superficial area of the part to be 
treated, but without focal lenses; on the other hand by the 
concentrated and condensed energy of the arc it is to be 
understood that the energy of the arc is used at its focal 
spot, and through focusing or condensing lenses of quartz, 
as per the method of Finsen. 

Of the apparatus described in the following pages, the 
Finsen, Finsen-Reyn, and the author's arrangement of the 
marine searchlight, with a water-cooled chamber, formed by 
means of two focal lenses of quartz, are the only mechanisms 
by which the energy of the arc is not only concentrated, but 
condensed as well. The marine searchlight as ordinarily 
used, the Victor or London Hospital lamp, the iron electrode 
lamp, and the apparatus of Bellini are all arranged for con- 
centrating the light, but not for condensing, i.e., with focal 

The essentials for a light mechanism for the treatment 
of lupus vulgaris and other skin lesions, as per the method 



of Finsen, or for the treatment of other conditions to be 
subsequently considered, are: 

( 1 ) A sufficient intensity of electric current which pro- 
duces lire luminous output 

(2) An effective luminous output <>n the skin of the 
patient : That is a beam of light rich in a complex of the 
energy of all the frequencies from the blue on op to the 
ultra-violet, which is at once both bactericidal and capable of 
exciting tissue reaction. By this complex of wave energy 
a deeply penetrating effect is secured, as well as the super- 
ficial action upon the skin, due to the absorption of the 
shorter wave lengths or ultra-violet. 

(3) Tin losses of effective energy between the arc and 
the skin of the | atient : This is by reason of the position of 
the arc and the relation of the patient to it t for the nearer 
the source of light the greater the energy. This is according 
to fundamental physical law, i.e., that the intensity of light 
varies inversely with the square of the distance, but it is a 
law which holds good only for non-concentrated light. 

(4) The influence of the media traversed; that is, losses 
by reflection or absorption: All media, air. water, glass, 
even superimposed quartz Imses weaken the force of the 
energy from the arc. Mirrors even used to rellect the light 
are a source of loss, but act better than the small lenses of 
quartz. Silver mirrors, for example, reflect only 92% of 
the visible spectrum, while an alloy (41% Cu -f- 26% Xi + 
24% Sn-f 8% Fe-f- 1% Sb) known as the Brandes-Schu- 
mann/ reflects only 50%, but reflects ultra-violet more than 
other metals. 

Mirrors of the Brandes-Schiunann alloy take a very good 
polish, and resist the action of the air. Steel might also serve 
as a reflector. 

Victor Schumann, to whose research is due the measure- 
ment of the shortest wave length yet recorded, is authority 
for the statement that metal mirrors of rnaguatta, an alloy 

Quoted by Freund from Fhystk Zeitschr., 1900. Vol II, p. 176. 

Fig. 54 —Therapeutic Arc Lamp of 25 to 40 amperes, direct 
current; require n . * water cooling for shell; is very useful in skin 
diseases and other local conditio! 


of aluminum and magnesium, reflect not only the visible 
spectrum, but the ultra-violet very satisfactorily. 

(5) Compression to render anaemic the tissues to which 
the application is to be made must be considered in order 
that the effective energy need not be absorbed by the skin to 
too great an extent. 

(6) A comfortable position of the patient in relation 
to the light mechanism is also a requisite, as well as a 
means of depriving the light energy of its heating effects. 

The experiments of Bernard, Morgan, Freund, Bie, 
Leredde and Pautrier would indicate that the shorter and 
more frequent the wave lengths the more useful they are: 
(1) in bactericidal activity, (2) in exciting tissue reaction. 
On the other hand, the longer they are the deeper they pene- 
trate. From this the conclusion is reached that the fre- 
quencies between the two extremes are the most useful, that 
is from the blue into the ultra-violet. 

Nature of Electrode Contacts. — When the electrodes sup- 
plied to an arc lamp are either iron, or, in the author's judg- 
ment, iron incorporated into the mass of the carbons, there 
is a very marked contrast between the color, and that from 
carbon electrodes alone. The light from carbons alone is of 
a dazzling whiteness, while that from iron and carbon shades 
from an intense dead or blue white to a bright violet color. 
Iron is very rich in the violet and ultra-violet frequencies, 
but exceedingly poor in the longer and slower frequencies, 
and, therefore, of limited power of penetration. While these 
intense chemical activities are of the greatest value, they 
need to be associated with the longer wave length of that 
part of the spectrum known as blue, in order to secure the 
best results. 

For several years the author has used lamps of from 
25 to 80 amperes with the best carbons obtainable, carbons 
through which a core of wire in the shape of an iron rod 
has run axially, or electrodes in which iron has been incor- 
porated in the mass of the carbon. The latter are the better, 
and they can be obtained in this country from the manu- 



facturers of arc lamps, or directly from the carbon -elect rode 
manufacturers or importer. As the spectrum of carbon is 
slightly deficient in blue, as compared with solar light, the 
addition of iron is an advantage. By this comhtnatku 
iron and carbon a spectrum very rich in the visible chemical 
frequencies, or blue, indigo and violet, as well as the invisible 
or ultra-violet frequencies, is combined with that of iron. In 
this connection the following is of interest: 

Arc Light Electrodes. — Recently Vogel 1 states that ex- 
periments for the purpose of ascertaining the chemical rela- 
tions which take place in an arc light between carbon elec- 
trodes containing ingredients intended to increase the light, 
have determined that the acid fumes of metallic salts rather 
decrease it than otherwise, being bad conductors of elec- 
tricity, and also poor dispensers of light. On the other 
hand, the conducting and light-emitting powers of alkaline, 
alkaline earth and rare earth metal fumes are very good, and 
the results of value, when the loss of energy caused by the 
vaporization of the substances is compensated for by the 
increased concentration of the gases, and the temperature 
of the arc raised by an internal chemical decomposition ini- 
tiated by the introduction of free ozone. The essentially 
novel and characteristic feature of Voxels invention, which 
produces the increased emission of light, is the separation, 
by means of a carbon partition, of the materials yielding 
oxygen from the light-emitting substances, and the central 
arrangement of these passages, in order th:it the oxygen may 
only reach the vapor of the illuminating substances after 
being ozonized. 

However, if one recalls the photosphere of the sun, 
formed as it is of a * 'colossal storm of rain and hail, of 
liquid and semi solid diamond," that is chemically [Hire car- 
bon, and that life is sustained by the radiance from the 
photosphere, the conclusion is forced that, after all. there is 
nothing better for phototherapeutic work than electro^ 
the purest carlmn obtainable. 

The Etectro-Chemist and Metallurgist, April. 1904 


The Type of Mechanism Selected is Governed by the 
Nature of the Work to be Done, i.e., the Pathology. — The 
first point, then, to be considered is the arrangement of 
mechanisms to be used for the purpose of concentrating the 
chemical frequencies of light, or in the method introduced 
and practiced by Finsen, of hot only concentrating but con- 
densing the light frequencies as well. If the condition to 
be treated is one involving extensive and well-organized in- 
filtrations, as lupus vulgaris, for example, then an arrange- 
ment of mechanisms utilizing to the full the chemical fre- 
quencies of a source of light, from 25 amperes upwards, 
should be selected, for here a great quantity of light is 
needed. They should be used preferably with focal lenses, 
for the maximum of energy is at the focal spot. 

If, on the other hand, the lesion is more superficial and 
less well organized, a source of light of less amperage is 
sufficient, the small iron electrode arc lamps, for example, 
while in many recent and still more superficial conditions, a 
source of light giving ultra-violet frequencies only, as from 
the spark condenser lamp, is of value. This latter fact is 
due, as has been pointed out, to the fact that ultra-violet 
frequencies have very little penetrant power, and are, there- 
fore, inadequate, where a profoundly penetrating effect is 
desired. With these latter mechanisms the use of focal 
lenses is not imperative. 

To Finsen the profession is indebted not only for the 
careful preliminary study and investigation showing con- 
clusively the role of these frequencies in skin diseases, but 
also for the application to therapeutics of a scientifically con- 
structed apparatus for the use of concentrated electric-arc 
light energy. Similar apparatus had long been used in 
physical and medical laboratories. In the Vienna Institute 
of Experimental Pathology, apparatus constructed exactly 
the same had been used for many years to project light by 
Professor Paltauf, and formerly by Professor Striker. 1 


4 66 

in i 

In his experiment as to the action of light, Widniark/ 
in 1889, made use of the same kind of apparatus* All of 
which is illustrative of the faet that the means to the at- 
tainment of a definite end in all matters of scientific develop- 
ment lie at our door awaiting the interpretation of and appli- 
cation by the intuitive intelligence. Such is the order of 
genius possessed by Finsen, and having proved by his ex- 
perimental work the action of light he was at once able to 

!— </' 

* -.j 

Fig. t6> — a, support of the apparatus; b t support of the tubes; 
c, support of the lamp *. d t positive carbon; </\ negative carbon; 
e t water feed; f, f\ rubber tube for water inflow; i. rubber tube 
for water outflow; m, entrance of W&teT into cooling chamber; /, tube 
with lenses; q. metal cylinder for the cireidah"ii "I water; r, r r , 
to render the rays parallel; s. lenses lu render the rays 

supply the needed apparatus for the utilization of the intense 
chemical frequencies of li^ht energy from an electric arc. 
His first therapeutic applications were marie with concen- 
trated sunlight, but it was not possible to obtain in that way 
sufficient energy, and, moreover, in northern latitudes, as 
that of Denmark, the sun was not always in evidence. 

Finsen \s Concentrator. — Finscn\s apparatus consists of a 
telescopic tube, by means of which the divergent rays of an 
electric arc are collected into parallel rays. These parallel 
rays are then collected into a cone, the apex of which is 

a Quoted by Freund. 


allowed to fall UpOti the part of the skin to be treated. 
Ftg. 16 gives a diagrammatic cut of Hnsen tube. This 
tube, which is the connecting apparatus between the source 
of light energy and the patient, consists of 2 metal cylinders 
telescoped one into the other, each one of which contains 

Fig, 17. — Fin sen Apparatus. 1 

two plano-convex lenses of quartz. These two parts of the 
apparatus may be separated by a rack and pinion movement. 
The various lenses are so proportioned as to size that 1 and 2 
have together a focal distance of 12 cm., while 3 and 4 have 
a focal distance of to cm. 

By the lenses 1 and 2 nearest to the source of light, the 
divergent rays of the electric arc are gathered into a bundle 
nf parallel rays: then by the action of the lenses at 3 anil 4 
these parallel rays converge on the surface to be treated. 
This is about 10 cm, outside of the lens marked 4. In the 

'From Freund, Radiotherapy and Philothcrapy. 


original tube the water chamber was fixed between lenses 
3 and 4, and kept tilled with distilled water for the purpose 
of absorbing the thermal frequencies. This part of the 
cylinder is in turn surrounded by an additional chamber 
through which, by an afferent and an efferent system of 
rubber tubes, connected with the source of water supply, cold 
water i>< kept circulating through the mantle surrounding 
the water chamber at the distal en<l id the tube, 1 Otherwise 
the water becomes boiling hot. 

Alternating Versus Continuous-Current Arcs for Coo* 

cent rating and Condensing Light Energy* — For his source 
of light energy Finsen uses a continuous-current electric arc 
of 80 amperes, He estimates its light intensity at 40,000 
candle-power. An alternating-current electric arc is not 
suitable where concentration of the light energy is desired, 
for, as has been pointed out under the physics of the electric 
arc, there is* no longer a continuous flame, but the arc is 
alternately lighted and extinguished at every reversal of the 
current The tight is, therefore, unsteady and unsuitable 
for concentration. 

Resistances to Cut-Down Voltage* — The E* M. F., 110 
volts, of the coiitinuou> current as supplied from the 
mains, is greater than is required for the operation of an 
electric arc. This is true whether an arc of 80 amperes, 
or arcs of greater or less am tre used. In the au- 

thor's use of an 80-ampere arc to operate a Finsen tube a 
suitable resistance or rheostat capable of using up the extra 
voltage is used. This is also done with 25 and 50-ampere 

The Necessity for IK aw Wiring to Carry Large Cur- 
rents. — The wiring for arc lamps must be heavier, i.e., capa- 
ble of carrying greater amperage than for the ordinary 
electric lighting of dwellings. This varies according to the 
current consumed by the arc. For an 80-atnpere arc a 
heavy, well-insulated wire is required. 

'Vladtmar Bit\ The Phils. Med. Journal Oct 4, 1899. 


Not Only Light Requisite but a Quantity of Light. — 
In the selection of an electric arc lamp the reader will re- 
call that it is not only light that is needed, but a quantity 
of light, and that the amount of light is not increased per 
unit of area with the current, but the size of the crater is 
increased, which increases the amount of light emitted. 
This is true with given carbons at a given distance apart. 
With both amperage and larger carbons, there is still a fur- 
ther increase in the size of the crater, and consequently in the 
unit of area, which means still more light, and especially 
more of the valuable short and high frequencies so active 

The Position of the Finsen Apparatus in Relation to the 
Arc. — Finsen's 8o-ampere arc is suspended from the ceiling 
(or it may be adjusted upon a very high table if desired, 
either iron or iron-covered). In the Finsen Light Institute 
the arc is suspended from the ceiling, as is shown in Fig. 17. 
There are arranged around a single lamp, four of the con- 
centrators or tubes described, each in turn being secured to 
an iron in order to utilize its energy for the simultaneous 
treatment of four patients. This ring in turn is fixed to the 
ceiling by four iron supports. The spaces between the single 
concentrators are filled with asbestos plates, in order that the 
operators and patients may not be exposed to the action of 
strong light. 

The apparatus is movable up and down as is shown by 
the pendant drop attached to an arrangement of pulleys. The 
concentrators are adjusted at an angle of about 45 degrees in 
relation to the arc, because it is at this point that the greatest 
energy of the arc is to be obtained. In this way the points 
of the carbons are exactly in the focus of the proximal lenses 
of all four of the concentrators. 

Water Cooled Compressing Lens. — As the light, how- 
ever, from this doubly cooled apparatus, i.e., water chamber 
and superimposed mantle or jacket, still produced too great 
heating effects, Finsen devised a hollow compressor con- 
sisting of a plate of quartz and of a plano-convex lens of 



quartz both framed in a conical brass ring, carrying two 
small tubes and follf arms, To eacb arm elastic bands are 
secured in order to adjust the compressor with equable pres- 
sure to tbe part to be treated, while the two small tubes 
nected with the interior chamber of the compressor are again 
in turn connected to a source of water supply by a system of 
efferent and afferent tubing providing for the constant circu- 
lation of cold water. In this way the remaining heat is done 
away with, while at the same time from the firm and equable 

Fig. 18. — Compressor; a, a\ leases of quart2; b, tube for the 
inflow of Wftter; b\ tube